LATTICE ENERGY OF IONIC SOLIDS

Size: px
Start display at page:

Download "LATTICE ENERGY OF IONIC SOLIDS"

Transcription

1 ********************************************************** CHAPTER 2 LATTICE ENERGY OF IONIC SOLIDS **********************************************************

2 6 2. INTRODUCTION One of the fundamental problems in the theory of solids is the calculation of the binding energy of the crystal. It plays an important role in understanding the nature of the interionic forces and their effects on thermal, elastic and anharmonic properties. The crystal energy or lattice energy of an ionic compound may be defined as the energy required to separate a formula weight of its ions by infinite distances. The simplest group of crystals to deal with in this respect are the ionic crystals, for which the theoretical treatment of ionic lattice 2 energy was first made by Bom and Lande. The evaluation of lattice energies of diatomic crystals using appropriate forms of interaction potential functions, has been a subject of extensive study. There are several theoretical models dealing with the calculation of lattice energies of ionic crystals apart from the 3-5 experimental method based on the Bom-Haber cycle. Comprehensive reviews on lattice energy calculations are given by 6 7 Sherman and Wad ding ton. It is well known that it is not possible to establish a stable equilibrium in ionic crystals unless other forces are present. Hence, in order to account for the stability of ionic crystals it is necessary to introduce forces between the ions that are noncoulombic. The history of the development of the theory of lattice energies is largely on account of the development of

3 62 the ideas about these noncoulombic forces. There are several expressions for the evaluation of the lattice energy, which involved these forces. Born, Born and Lande, Madelung and 4 Haber developed the theory of ionic crystals and devised formulae which permit the calculation of the lattice energy of an ionic 5 crystal. The Born equation was improved by Born and Mayer by considering the repulsive term on the basis of the ideas of wave mechanics. A simpler approach to lattice energy calculations was suggested by the Russian Chemist Kapustinskii. His expression requires no Madelung constant and hence no knowledge of the crystal structure. 2 Ladd and Lee used parameters like compressibility coefficients, cubical expansion coefficients and the zero-point energy terms for the evaluation of lattice energies 3 of alkali halides. Kudriavtsev developed an expression relating the mean sound velocity to the lattice energy of ionic crystals. The quantum mechanical calculations of the crystal binding of ionic 4 5 crystals were given by Hylleraas and Landshoff. The details of the various equations mentioned above are discussed in detail in Section 2.2. The direct experimental determination of lattice energy is difficult and has been carried out only in a few cases. Lattice energies can, however, be related to other measurable energy quantities by means of a thermochemical cycle due to Born and Haber^ 4 (the Born-Haber cycle). The lattice energy given by the Born-Haber cycle is an experimental lattice energy and

4 63 is not dependent upon the nature of the assumptions made about the bonding in the crystal. A brief review of the different theoretical approaches for the evaluation of lattice energies of ionic crystals is presented in the following section.

5 THEORIES OF LATTICE ENERGIES Bom's Theory of Lattice Energy The crystal, or lattice energy of an ionic compound may be defined as the energy required to separate a formula weight of its ions by infinite distances. Conversely, it is also the energy released when a formula weight of a substance is produced by bringing together from infinite distances the necessary number of positive and negative gaseous ions. The crystalline state properties of ionic solids mainly depend upon the nature of the chemical bond between the atoms and the interaction energies. Whether an ionic or covalent compound is formed in the chemical union of atoms is dependent, not only upon the difference between the amount of energy required for ionization, but also upon the lattice energy of the salt produced. Solid ionic compounds are not made up of individual molecules. Instead, the crystal lattice is built up by the deposition of a regular array of ions in which each ion is surrounded by a definite number of ions of opposite charge. For example a crystal of sodium chloride may be regarded as a huge cluster of ions in which six chloride ions are grouped spatially around each sodium ion and six sodium ions are grouped around each chloride ion. The number of ions which may be grouped around a central ion is determined by the radii of the respective

6 65 ions involved. In the vapour state, however, ionic compounds are essentially molecular in composition. Such molecules, as for example, NaCl, are polar in their structure and can be considered as ion pairs, in which the portion of a molecule occupied by the sodium atoms is positively charged and that part containing the chlorine atom is negatively charged. The pair of ions in a gaseous molecule of an ionic compound are probably held together at an equilibrium distance from each other as a result of a balance between the forces of attraction (between the two oppositely charged ions) and the forces of repulsion which come into play at short distances. Consider a single molecule consisting of a pair of charges Z^e and Z2e. The electrostatic potential energy between these two opposit.ely charged ions may be expressed as pp _ ZlZ2e electrostatic r the Z values represent the integral changes on the two ions, e is the charge on the electron; and r is the distance between the centres of the two ions. However, equation 2. represents only the electrostatic energy between two ions, whereas, within a crystal, the same two ions are subjected to additional coulombic forces from other ions. Furthermore ionic crystals are not composed of simple ion pairs, but of ionic clusters in which each cation is surrounded by a definite number of anions and each anion is likewise encompassed by a fixed number of cations. Therefore, in order to calculate the coulombic energy of any single ion,

7 66 allowance must be made for the number and arrangement of neighbouring ions of both signs. Because of electrostatic interactions with surrounding ions the coulomb energy of a single ion is greater than indicated in equation 2. by a factor typical of each kind of crystal structure. This factor, known as Madelung constant and designated as A, is the summation of the electrostatic contributions of neighbouring ions and depends on the type of lattice in which the ion occurs. As a result of this summation, the coulombic energy of a single ion may be indicated as -A.e/r. The electrostatic potential energy per ion pair is A Z Z e2 pp _..^ o 9 r electrostatic ~ r *** where A is the Madelung constant and the negative sign indicates that energy is released when the two ions station themselves within the crystal. The Madelung constant (A) is a correction factor to take care of additional electrostatic forces exerted by neighbouring ions upon an ion pair and is entirely dependent upon the geometry of the crystal. The following are the values of Madelung constants for a few crystal lattices. for sodium chloride lattices, A = for cesium chloride lattices, A = for sphalerite, ZnS lattices, A =

8 67 In addition to the coulombic forces which operate between ions there are repulsive forces which arise to prevent ions from approaching each other too closely. These forces originate as a result of a general mutual repulsion of the electron clouds of atoms and ions whenever these clouds penetrate each other and the electrons do not form a bond with a common electron pair. As a result of the repulsive forces opposing those of coulombic attraction, oppositely charged ions come to equilibria at definite distances from each other. The forces of repulsion become strong when the electron shells of two ions are in close contact but decrease rapidly with distance. The factor of repulsion is 3 n difficult to calculate and is usually represented by Born0 as B/r, where B is a constant and n is the power of the distance to which r (the distance between ions) must be raised to give the correct repulsive force. The total lattice energy per ion pair within a crystal of the MX type may be indicated as A Z Z2 6. Be2 U... + MX n 2.3 and the total energy per formula weight of MX is U N A Z Z2 6 + N. Be2 n 2.4 wtere Uo is the lattice energy and N is Avagadro's number.

9 68 In those crystal types where r and n can be determined experimentally, it is possible to calculate the repulsive coefficient B, and if we omit some of the mathematical steps involved, a more general Born equation for lattice energy may be stated as: -N A Z Z e2 U = ( - -) o n r Bom-Mayer Equation g Born and Mayer improved equation (2.5) by considering the repulsive term on the basis of the ideas of wave mechanics, which indicate that the electron density falls off exponentially with distance from the nucleus. Accordingly, they wrote the r/p repulsive term in the form be, where b is a constant similar to the B in equation (2.4), and p is a constant for a given species; thus the expression for lattice energy becomes U N A Z. Z e2, b e r/p 2.6 Equation (2.6) gives U = 0 and r =», i.e., the potential energy of the molecule is zero when the ions are separated from each other. As the ions are brought close to each other the attraction and repulsion potentials increase in the manner shown schematically by the dotted curves in Fig. 2..

10 69 The net potential energy U is the sum of the repulsion and attraction potentials, and is the solid curve in the figure. The latter curve shows a minimum at r = r and U = U, which o o correspond to the equilibrium separation and binding energy of the molecule. For this minimum we must have and hence differentiation of equation 2.6 with respect to r gives Z Z2 6 b e -r0/p or -r /P b e o P Z Z2 e 2.7 On substitution of Eq. 2.7 into Eq. 2.6, we obtain U 2 -N Z Z e = ( - ±-) ro ro 2.8 The values of P (calculated from compressibility measurements) are found to be the same for most crystals, being equal to X. If the number of ions in the stoichiometric formula of the crystalline substance is then the number in a gram mole is N v. The Born-Mayer equation 2.8 may then be conveniently rewritten as

11 A ttraction (-3 <= Repulsion (+3 Distance of Separation - r Fig. 2.. Potential energy diagram for ionic bonding.

12 70 U A (NV/2),NV N e2 Z ) (- 2, 2.9 and writing the structural coefficient for one ion, a = this becomes av N e zi z2 p U = -(-y) ( ( - p 2.0 Here a has different values for different structure types and is independent of the Madelung factor A. Kapustinskii Equation 0 Kapustinskii suggested a simpler approach to lattice energy calculations. He found that on passing from one type of structure to another, the change in a was proportional to the change in the interatomic distance r for the differing coordination numbers. Each crystal may then be supposed to transform into a sodium chloride lattice (coordination number 6) without change of lattice energy (i.e., stability), if the coefficients a and v are simultaneously modified so as to have the values corresponding to a sodium chloride lattice; thus the following substitutions are made: a. r = ra + V the sum of the ionic radii (in A) for coordination number 6; these values are now known for most ions.

13 7 b. a = z =.74756, the value of the Madelung factor (f, > for the NaCl lattice o c. p = A. 2 d. N e = K cal, the product of fundamental constants. Thus Eq. 2.0 becomes U Z± Z2v (r + r ) a c [ (r + r } a c 2. where ra and r are respectively the radii of the anion and cation, v is the total number of ions in the stoichiometric unit which specifies one mole of the substance, e.g. 2 for NaCl, 3 for CaF2, 5 for A203- Kapustinskii' s equation is the algebraic sum of two quantities. The attractive (negative) term represents the net effect of the Coulombic, point-charge interactions among all the ions in the lattice. The repulsive term arises from the non-coulombic interaction between the electron clouds on neighbouring ions. The usefulness of the Kapustinskii's equation lies in the fact that it is possible to calculate the lattice energy of any crystal, even if its structure is unknown, by assuming it to possess a sodium chloride lattice and using the appropriate values of the ionic radii.

14 72 Bom-Haber Cycle The lattice energy of an ionic compound is the energy set free when the crystal lattice is formed from free gaseous positive and negative ions. The process of gaseous ions condensing to form ionic crystals is of rare occurrance and is therefore largely of theoretical interest only. The direct determination of the lattice energy of an ionic crystal has been carried out for only a few compounds. In the majority of cases it is not possible to measure this energy 3 directly; however a cyclic process has been devised by Born 4 and Haber which relates the crystal energy to other thermochemical quantities. Where the energy of formation of a crystal from its component elements is known, it is possible to split this value into the energies of a number of processes, which may be postulated as constituting the intermediate steps in the formation of the crystal. By means of a circuitous procedure it is possible to calculate algebraically the theoretical lattice energy of a crystal. For example, consider the formation of sodium chloride from elementary solid sodium and elementary gaseous chlorine. It may be assumed that the sodium metal is evaporated and the diatomic chlorine is dissociated; then the alkali atoms are ionized, and the electrons so obtained are transferred to the halogen atoms so that positive sodium ions and negative chloride ions are left in the gaseous phase. The various steps involved in this cycle

15 NaCl(S) (i) > Na (g) + Cl (g) KJ <iv) (ii) + I E Na(S) + ^Cl2<g)4 (ill) +U + igd c T Na(g) + Cl(g) 2.2. Measurement of the lattice energy using the Born-Haber cyclic process, (+) and (-) indicate energy released and absorbed respectively.

16 73 are i. decomposition of the solid into the constituent ions, ii. the formation of neutral atoms from ions, iii. iv. the formation of atoms, and the formation of standard states. standard states of elements from the the solid from its elements in their This is illustrated in Fig. 2.2 for the case of the NaCl crystal. The algebraic sum of the energies in the processes (i) to (iv) is equal to zero. The energy UQ for the process (i), which is the cohesive energy of the ionic lattice, is therefore calculated from the known energies for the processess (ii), (iii) and (iv). In process (ii) the energies involved are the ionization energy, I of the sodium atom and the electron affinity, E, of the chlorine atom. In (iii) sodium atoms combine to form sodium metal while chlorine atoms combine to form chlorine (Cl2) gas so that the energies involved are the cohesive energy U of the sodium metal and half the dissociation energy D of the Cl2 molecule. Finally the heat of formation, Q is involved in process (iv) when NaCl is formed. The lattice energy Uo is therefore given by U = Q + U 4d+I - E o w c 2 For NaCl in units of kilocalories per mole, Q = 98.6, U = c 26.0, D = 57.9, I = 83.3 and so the lattice energy, UQ = 89.2 K cal/ mole. This value agrees with that obtained by direct measurement

17 74 to well within the limits of the experimental errors. Lattice energies derived from the Born-Haber cycle (Equation 2.2) are experimental values which are independent of any assumption about the cohesive forces in the crystal. On the otherhand, the derivation of equations 2.5, 2.8, and 2. does assume the cohesive forces to be completely electrostatic in nature. Kudriavtsev's Relation 3 Based on Kudriavtsev's theory an expression which relates the mean sound velocity U with the lattice energy U of a m o crystal can be derived and is as follows: MU rn ( UD) 2.3 where Y, M and U represent the ratio of specific heats, m molecular weight of the crystal and mean sound velocity in the system respectively, n^ is a constant which depends upon the lattice structure and the values of n^ that can be used are 3, 5, 7, 9 and 0. The mean sound velocity, can be obtained from the experimental determination of the velocity of longitudinal and shear wave propagation in polycrystalline solids or from the single crystal elastic constants data making use of the Voigt-Reuss- 24 Hill approximation.

18 75 Quantum Mechanical Prediction of Lattice Energies 4 Hylleraas applied a general quantum mechanical treatment to the calculation of lattice energies. He used one-electron wave functions of the hydrogenic type with nuclear screening so that the entire computation could be performed analytically. The approximate wave functions used by him were * = exp t-(z - g) -] h with Z = for hydrogen and 3 for lithium, a^ is the Bohr unit o distance (0.58 A).

19 76 Lattice energy calculations based on interionic potentials A large number of interaction potential energy functions have been suggested by different workers from time to time. These potentials have been used to compute the various properties of ionic crystals. These new approaches differ from one another in the form of the repulsion energy considered. A few of such studies are outlined here. The lattice energies of all the alkali halides have been 20 calculated by Prakash and Behari using the following expression: 2 <b = + A log ( + ~) - + U y r e 9 6 r r The first term on the RHS in the above equation is the well-known Madelung energy; the last term is the zero-point energy, the 2nd term is the logarithmic form for the overlap repulsion. A, B and C are parameters. 4 Dass et al have given the following complete form of the potential energy function which takes into account all the forces of interaction between the ions at a separation distance. <f>(r) A exp ( } r P C_ 6 r D_ 8 r _ 2 2, v Z e + <22) 2 r' n e aia2 7 r Y 2.6

20 77 where Z is the valency of the ions, e the electronic charge, and o<2 are the polarizability values of the two ions and A, C, D are constants. In the above equation the first two terms represent the electrostatic and overlap interactions respectively, while the third and fourth terms are due to van der Waals forces. 3 To account for the polarization forces, Rittner introduced the fifth and sixth terms. The covalent energy has been represented by a constant Y. 92 Using the modified Bom model, Gupta and Sharma has proposed the expression for lattice energy taking into account several interactions. ijj (r) e 2.7 where a is the Madelung constant, e the electronic charge, r the equilibrium interionic distance, X the repulsive parameter, C the dipole-dipole interaction parameter, D the dipole-quadrupole interaction parameter, e the zero-point energy and n the index of the repulsive term. The above equation has been used by 92 Gupta and Sharma to evaluate lattice energies of several heavier halides. A generalised logarithmic form of repulsion energy has been suggested by Thakur and Pandey the lattice energies. to calculate

21 78 U.. r4 B, A l08 <5 * -H> r 2.8 where A and B are potential parameters and n =,2,4... A new type of repulsive term in the interaction potential has been suggested by Usha Puri4^, which is found to yield better results than those obtained by logarithmic form (Eq. 2.8} for the repulsive term of interaction potential. cj>(r) 2 Z2 2 r Z b -Ar e r 2.9 f(r) is the potential energy per unit cell, a is Madelung constant, Z^e and Z^e are the charges on the ions, r is the ionic separation. Z is the number of nearest neighbours of any ion. The constants ^ and b in the exponential term are known as potential parameters. 44 Thakur and Sinha have proposed a modified form of the 08 Kapustinskii-Yatsimirskii equation using logarithmic form of lattice potential energy and is given by U = n Z% Z2 (r +' r } e a [ - log(j ( + -)] (r + r }' c a n Z2, where r and r are the cationic and ionic radii; p is a constant c a equal to 2^, In is the total number of ions present in the

22 79 molecular formula of the compound; and 2^ are the ionic charges. The above equation has been applied to calculate the lattice energies of alkali halides and alkaline earth chalcogenides. The Born-Mayer equation in its generalised form without the use of the compressibility term has been further modified 78 by Thakur et al. Their empirical expression for lattice energy calculations, based upon the logarithmic form of potential energy is given by N A e2 Z Z U = v " O80 (a + P r0 )] *' 2,2 o where a and p an parameters. For alkali halides, a =.05 and p =.6046 X2. Taking into consideration the repulsive interaction between nearest neighbours as well as next nearest neighbours, Shanker 8 et alt has obtained the following expression for the evaluation of lattice energies of alkali and silver halides. w. V V M < «* _> r r where the first term on the right of above equation represents the Madelung energy (am the Madelung constant, Ze the ionic charge, r the interionic separation). The second and third terms are the van der Waals dipole-dipole and dipole-quadrupole energies.

23 80 The fourth and the last terms represent the short range overlap repulsive interactions operative between nearest neighbours (unlike ions) and also between next nearest neighbours (like ions). M and M' are the numbers of first and second neighbours. A brief review of work on the lattice energy calculations of ionic crystals is presented in the following section.

24 8 2.3 BRIEF REVIEW OF EARLIER WORK ON THE EVALUATION OF LATTICE ENERGIES OF IONIC CRYSTALS Studies on the theory of lattice energies of ionic crystals have been undertaken as early as in 98. There have been a large number of attempts to evaluate lattice energies of ionic 9 crystals. The quantitative theory of lattice energy has been 8 developed mainly through the pioneering works of Born, Born and Lande, Madelung and Haber. The various lattice energy calculations were reviewed comprehensively by Sherman6 and 7 Waddmgton. Of all the ionic crystals, alkali halides are relatively easy to subject to theoretical treatment since they have simple crystal structures and are bound by the well-understood Coulomb forces between the ions. A large number of workers have calculated the lattice energies of alkali halides with different approaches. The principal calculations by the classical ionic 2 6 theory have been made by Mayer and Helmholtz^, Verwey and deboer, Huggins and by Seitz. Ladd and Lee have used a method to compute lattice energies eliminating the need for 'basic 0 radii'. Kapustinskii has also calculated lattice energies, but his values are rather low. The theory of Born and Mayer 5 has been extended by the work of Landshoff using the methods of quantum mechanics. In addition to the correction terms of 5 Born and Mayer, Landshoff has incorporated additional interactions

25 82 related to the superposition of the electron clouds, the attraction between electrons and nuclei and the mutual repulsion of electrons. 6 Lowdin has calculated the lattice energies of LiCl, NaCl, KC and NaF. Lattice energies of alkali halides were also estimated 7 8 IQ by Cubbiccotti, Saxena and Kachhava, Pandey and Prakash 20 2 and Prakash and Behari. Pande has used the Bom-Mayer potential to estimate lattice energies. An exponential form of 22 repulsive energy has been suggested by Dixit and Sharma Pandey. Sharma has used the Rydberg potential function. A logarithmic form of repulsive potential has been used by Misra 25 et al. A modified electron gas treatment has been employed by Cohen and Gordon. Calais has reviewed the lattice energy 28 calculations. Kai Wen and Sho have made calculations on the basis of the effective nuclear charge and rate of cation polarization. A semi-empirical free model with atomic constants as parameters has been used by Shorezyk^. Many workers ^ have also attempted the lattice energy calculations of alkali halides Puri et al, Andzelm and Piela, Saxena, Garg et al, Zhadonov and Polyakov, Sinha and Thakur, Usha Rani Thakur and Sinha44, Singh and Nirwal45, Shankar et al46, Singh and Shankar, Lister, Dedkov and Temrokov, Nirwal and Singh, Shanker and Agrawal, Islam, Shanker et al. and Nirwal and Singh have obtained the lattice energies using different approaches. Dissociation energy studies have been used for the 55 estimation of lattice energies of alkali halides by Jha and Thakur, and

26 Yadav and Kaur et al. Singh et al has obtained lattice energies from a relation between the lattice energy and coefficient of thermal expansion. Lattice energies have also been obtained by Yamashita and Asano, Shukal et al», Kaur et al, Rehman 6 62 and Shams and Reddy et al. The lattice energies of alkaline earth oxides, sulphides, selenides and tellurides have been calculated by a number of 6 workers. Sherman has used the simple Born formula for the evaluation of lattice energies of alkaline earth oxides. Later Mayer 6 3 and Maltbie have used the Born-Mayer expression for the lattice energies, calculating the London dispersion energies from the 64 polarizabilities of the free ions. deboer and Verwey has recalculated the lattice energies of the alkaline earth oxides, because the Mayer and Maltbie interatomic distances differed significantly from those obtained from the X-ray data. Other calculations on these crystals have been made by Van Arkel and deboer, Fowler 68 and by Kapustinskii. Kapustinskii and Yatsimirskii, and Huggins 69 and Sakamoto have recalculated the lattice energies of all the alkaline-earth chalcogenide crystals Saxena et al, Kumari Kha et al, Pandey and Pant have obtained lattice energies of some alkaline earth oxides. Son and 73 Bartels have obtained lattice energies of MgO, CaO and SrO using a simple Born model. Cantor, Thakur, Upadhyaya and Singh, Thakur and Sinha, Thakur7, Thakur et al, Singh and Shanker 79 and Mackrodt and Steward have also estimated lattice energies of

27 oxides. More recently, Islam, Shanker et al. and Singh 8 et al. have also calculated the lattice energies of alkaline earth oxides. The lattice energies of alkali metal hydrides have been 4 calculated by Hylleraas using a quantum mechanical approach. 82 Lundquist has also calculated the lattice energy of LiH using 83 the same approach. Bichowskii and Rossini derived the lattice energy of LiH using Bom-Lande expression. Accurate values of the lattice energies are available from thermochemical data. KazarnovskiiP^ has used these values to calculate the exponent 7 in the Born repulsion coefficient. Waddington. has evaluated lattice energies of all the alkali metal hydrides using a simple Bom-Mayer expression, ignoring van der Waals terms. The lattice energies of alkali metal chalcide crystals viz. 85 L^O, Na^O, K^O, Rb20 and CS2O have been calculated by Morris, who considers these salts to be more ionic than the alkaline earth 7 oxides. Waddington has tabulated calculated values from the work of Sherman^ and West^. The lattice energies of the halides of univalent metals (other than alkali metals) viz. the argentous, the thallous and the cuprous halides were calculated by Sherman. 87 energies in these solids were recalculated by Mayer The lattice and by Mayer and Levy. Later Ladd and Lee have recalculated the lattice energies of the silver and thallous halides by a method avoiding the use of the Huggins basic radii, which are difficult

28 85 to fix for these salts. The lattice energies of these heavy metal 70 halide crystals have also been evaluated by Saxena et al, Gohel an Q Q? Qq and Trivedi, Murthy and Murti, Gupta and Sharma, Sharma ^, 94,95,.. t,96,97,,78,. 98 Thakur, Bakshi et al, Thakur et al, Jam and Shanker qq [in n-i Shanker et al, Shanker and Agrawal and Singh and Khare. The lattice energies of the divalent metal halides have been 6 02 evaluated by Sherman using the Born-Lande equation. Morris' has extended the theoretical calculation, again using the Born- Lande equation and has recalculated the thermochemical data. 03 McClure and Holmes have also recalculated the thermochemical data for lattice energies of the transition metal halides. The thermochemical lattice energies of the divalent transition metal halides have been further studied by Orgel, Griffith and Orgel and Hush and Pryce'*'^.

29 AIM AND SPE OF THE PRESENT WORK The study of lattice energies of ionic crystals play an important role in understanding a variety of phenomena of physical and chemical interest. Studies on the lattice energy of ionic crystals have been reviewed in the preceeding section in detail. The review work presented in this chapter reveals that a large number of interaction potential energy functions have been suggested within the frame work of the Born model by different workers from time to time in order to study the various properties of the crystals. While workers * concerned with phonon frequencies of ionic crystals have used the exponential form of Bom-Mayer equation for the repulsive part of the lattice energy, logarithmic forms for the same have been used by some workers interested in the study of chemical properties of crystals such as atomization energy, electron affinity etc. Previous attempts to calculate the lattice energy on the basis of such interionic interaction potentials, gave values which in several cases fall off the accurate data obtained from experimental and quantum mechanical calculations. There are also other instances in which these models are found to be inadequate in predicting correctly the elastic and dielectric properties of ionic crystals. The Born-Mayer theory has later been refined, with resulting improvement in the agreement between the calculated and experimental lattice energies for ionic crystals. The

30 87 refinements considered the small (a few kilo calories per mole or less) corrections to the lattice energy arising from van der Waals interactions and zero-point vibrational energy. The detailed calculation of the lattice energy of an ionic crystal according to interionic potentials requires knowledge of a number of input data, such as crystal geometry, compressibility at 0 K, interionic distance, etc. Measurements and correct estimations of these various terms are rather difficult and sometimes unpredictable. In the absence of any of these parameters one cannot obtain the lattice energy values by these potentials. The Kapustinskii' s equation for the calculation of lattice energy values which uses only ionic radii as input data, gives lattice energies which fall on the low side of the experimental 7 values. The Kapustinskii's equation has also been criticized for emphasizing the sum of ionic radii, r + r, whereas in many C 3 crystals the interionic distances obtained predominantly by anion- 42 anion contacts. The quantum mechanical calculations of the crystal binding of ionic crystals are tedious and very much elaborate. Such calculations have therefore been limited to 38 crystals like LiF and NaF which are composed of lighter ions + + containing only 2 electrons (Li ) and 0 electrons (Na and F ). The quantum mechanical calculations are not easily extendable to crystals of heavier ions. This is why most of the studies on ionic solids have been phenomenological in nature where the

31 88 potential parameters are fitted from the crystal data on compressi- 8 bility and interionic distance, as pointed out fay Sharma et al Such a fitting of potential parameters becomes much more complicated when the repulsive interactions between nearest neighbours as well as between next nearest neighbours are considered. Keeping in view the above limitations, the author has proposed some simple and straight empirical relations for the evaluation of lattice energies of alkali halides, alkaline earth 2 chalcogenides, alkali metal hydrides, alkali metal divalent halides and some heavy metal halide crystals. The lattice energies are directly calculated from the values of interionic distance. The calculated values for these ionic crystals are compared with the experimental thermochemical data. The agreement is considered to be support for the essential validity of the proposed relations. A suitable test of these lattice energies has been presented by calculating the valence electron plasmon energy and hence the other opto-electronic properties namely the Penn gap, Fermi energy, So-parameter and the electronic polarizability in the case of alkali halide crystals, and alkaline earth chalcogenide crystals. For the purpose, relations between the lattice energy and the plasmon energy are proposed for the above ionic solids. For an ionic crystal, the atomization energy (AH ) is of a importance as it gives a better idea of crystal stability than

32 89 lattice energy. The atomisation energy can be calculated in general, from the lattice energy through the relation: E = U - I + E a p in which E is the electron affinity of the anion and I the first ionisation energy of the cation). In the present study simple relations are proposed between the lattice energies and the heats of atomisation and heats of formation, the results of which are compared with the available experimental data. The present values of lattice energies are discussed in the light of those calculated from the different existing theories viz. Kapustinskii, Born-Mayer, Kudriavtsev's relations. The details of the opto-electronic properties and their expressions are described elsewhere in Chapter. i. New Relations proposed between the Lattice Energy and the Interionic Distance Simple empirical relations are proposed for the evaluation of lattice energies based on the assumption that a linear relation exists between the lattice energy and the interionic distance within a molecular group of compounds. These relations are applied to the alkali metal halides, alkaline earth chalcogenides, alkali metal hydrides, alkali metal chalcides, some univalent higher metal halides and some divalent halide crystals. The following are the empirical relations for various molecular group of compounds:

33 90 U = (rq)... Alkali halides 2.23 U = (rq) Alkaline earth chalcogenides 2.24 U = (rq) Alkali metal hydrides 2.25 U = (r ) Alkali metal chalcides 2.26 U = (rq)... Alkaline-earth divalent halides U = (rq)... Ga, In, T halides where U and rq are the lattice energy (kcal/mole) and the interionic separation (X) respectively. The constants in the above relations are unique in the sense that they represent the best fit with the experimental data. ii Relations between the lattice energy and the plasmon energy New relations are established between the lattice energy and the valence-electron plasma energy based on the simple assumption that a linear relationship between the two parameters is valid in the case of molecular group of compounds under study. U = 6.70 (few ) Alkali halides U = 24.3 Cho) ) Alkaline-earth ^ chalcogenides U 9.47 Chtd ) Alkaline metal hydrides 2.3

34 U = 9.3 (tio) ) Alkali metal p chaleides U = (Ixo ) Alkaline-earth p divalent halides The numerical constants in the above equations are also the result of a fit of the experimental data, similarly to equations 2.23 to In the above equations, lia) is the valence electron r 29 plasma energy (ev) which is given by Jackson on the basis of the plasma oscillations theory of solids as follows. tico 28.8 ( p)/ where Z is the total number of valence electrons given by Z. + Z A B (ZA and Zg are the principal valence states of the elements _3 composing the crystal). P is the density (g.cm ) and M is the atomic or molecular weight (gr.) of the solid. The expressions for the Penn-gap (E ) and the Fermi energy (Ep) in terms of tiw are given by * r* tl(0 - U/2 ev 2.35 and 5.K. UNI VERS! I Y LIBRARY, ANANTAPUR (tuo )4/3 ev P 2.36

35 92 3 The expression for electronic polarizability (a) (cm ) due to 28 Ravindra and Srivastava, which is derived on the basis of the well known Clausius-Mossotti relation and the Penn-like models is given by: a = (tiw )' P (tiw ) S p o 3 E M n m 24 3 x x x 0 cm d where M and d are the molecular weight (gr.) and density (g.cm } respectively. SQ is a constant for a particular compound and is given by E 4E L E J r e i 4E_ p iii Relations between the Lattice Energy and the Heats of Formation and Heats of Atomisation The following are the linear relationships established between the lattice energy, the heat of formation and heat of atomisation. f U = -.65 (AHq) Alkali halides U =.387 (AH ) Alkali halides U = 2.44 (Ah ) Alkali metal a hydrides where AH f is the heat of formation and AH is the heat of o a atomisation or atomisation energy in kcal/mole.

36 93 RESULTS AND DISCUSSION Lattice energies for several ionic solids viz., alkali halides, alkaline-earth chalcogenides, alkali metal hydrides, alkali metal chalcides, alkaline-earth divalent halides and some higher metal halides are calculated from simple empirical expressions taking interionic distance (rq) as the input data and the results of the calculations are presented in Tables 2. to 2.8 and Figures 2. to 2.6. The calculated lattice energies of these ionic solids are utilized to evaluate plasma energies from simple correlations proposed between lattice energy and plasma energy. The calculated plasma energy values are, in turn, used in the estimation of certain opto-electronic properties like the Penn gap, Fermi energy, SQ-parameter and hence the electronic polarizability, in order to test the applicability of the proposed relations. An experimental check on the calculated values of the lattice energies may be obtained from the experimental method based on the Born-Haber cycle. The lattice energy values obtained from the proposed correlations are well compared with those obtained from Born-Mayer, Born-Lande, KnpiiRtinRkii and Kudriavtsev's relations. The lattice energies obtained from the present approach for all solids agree closely with the experimental values than those calculated from other theories.

37 Figures 2. to 2.6 demonstrate the superiority of the present approach over other theories. The basic differences between various theories employed in the comparisons are critically analysed below: As it is well-known the principal interactions in ionic lattices are the static Coulombian interactions which give rise to Madelung's energy, van der Waals* interaction and the overlap force. Though the first two interaction terms are well established, no simple expression for the third follows from the theoretical considerations. As more acceptable forms of the overlap energy, the following two expressions are in frequent use: (i) The Born form'*'b/r, where b and n are adjustable parameters and vary from substance to substance. 20 On the basis of quantum mechanics, Seitz has suggested that this form is not rigoursly correct, although it may be a fair approximation for a shorter range fo r. 5 (ii) Born ' and Mayer proposed a repulsive term of exponential form a exp (-r/p), based upon quantum mechanical prediction. They took P =0.345 x 0" cm quite arbitrarily, for all types of ions and assumed that the constant a has ionic radii dependence. Because of the uncertainity of these assumptions, values of lattice energies calculated by different workers on different models differ largely, e.g. they differ by 25% in the 3 of Rb+ and 62% in the case of Li+ as given by Goldschmidt case 94

38 32 and Huggins and Mayer. Moreover, in this form, the repulsive potential is finite and electrostatic potential is - oo at r=0. Hence, the net interaction remains negative, i.e. attractive, which q 7 q looks unphysical. Mayer and coworkers subsequently modified this term and added another term which made the expression more cumbersome from the calculation point of view. 95 But the new expression did not exclude the ionic radii dependence and the above limitation in the vicinity of r=0. (iii) Another repulsive term of inverse power form br n was suggested by Born-Lande in the ionic interaction potential where b and n are constants and r is the distance between nearest unlike ions for a given crystal. But quantum mechanically, it may be a fair approximation for a short range of r. (iv) The lattice energies can be related to other measurable energy quantities by means of a thermochemical cycle due to Born and Haber3,4. The lattice energy obtained by the Born-Haber cycle is an exprimental lattice energy and is not dependent upon the nature of the assumptions made about the bonding in the crystal. One requires sublimation energy, dissociation energy, ionization energy, electron affinity and heat of dissociation to evaluate lattice energy of a solid by Bom-Haber cycle.

39 96 (v) The Kapustinskii's equation proposed a general method for the calculation of lattice energy values which uses only ionic radii as input data. The lattice energies obtained by this equation are often fall on the low side of the experimental 7 values. The Kapustinskii equation has also been critisized for emphasizing the sum of ionic radii, r +r, whereas in many crystals the interionic distances are detained predominantly by anion- 42 anion contacts. (vi) Kudriavtsev developed an expression relating the lattice energy UQ of a crystal with the mean sound velocity o MU = (Yn.U )/9. To calculate the value of mean sound m o velocity U, one requires the experimentally determined parameters of velocities of longitudinal and transverse wave propagation in polycrystalline solids or single crystal elastic constants data. The term n^ is a constant and has the values of 3, 5, 7, 9 and 0. Depending upon the suitability of different crystal structures, one has to change the value of nj from 3 to 0 to predict correct lattice energies e.g. for all NaCl-type alkali halides, the suitable value of n^ = 5; for CsCl-type cesium halides the suitable value of n^=7. (vii) As already pointed out, the detailed calculation of the lattice energy of an ionic crystal according to interionic potentials requires a knowledge of a number of input data such as crystal geometry, compressibility, interionic distance etc.

40 : I I 4) -H O < >s. I } o» X r j < s ' Born- Lartae Exptl. data Present study tn fa <4-0> 0C Ref.23 Eq <r <? M M o <r 76.5 o O' «f la *A f-* la la a ta (M la r- la o Exptl. data Ref.24 r- la 2 i M r- r t T ia O i j Table 2.. lattice energies (U), heats of formation (AH ) and heats of atomisation tohg) of alkali halides at 298 K < o V- < 0) o E N <~4 ura 3 cn H O' (-* a> c 0) 0) r-p u 4J o u Alkali halide Present study Thakur et al. Kudriavtsev Kapustinskii Born- Lande Born- Mayer Exptl. data Present study Eg.2.48 Ref.78 Refs.07,08 Ref. 7 Ref.6 Ref.78 Ref.89 Eg.2.23 Ref la LiF , LiCl (xi H -J » H <* u. 0) Z * u eg z U eg z *A O' * «z O' u. sc MS f- M O' NO On u 84.5 NO r- NO KBr r- NO fca sc as s r U. JD sr *~4 CJ JD X »A la r~~ ON <r Cf RbBr M3 On r** la ON M3 <r tr ON On I NO u. U) CJ ON ia a NO la CsCl a ON <r 59.9 O' <r 42.9 fca ON o<r A' CsBr o p-» r o ia NO <r Csl 7.79 a a.70 Average percentage deviation

41 calculated experimental Fig. 2.. Plot showing the relationship between experimental lattice energies (kcal/mole) of alkali halides and th calculated from Eq.2.23, Born-Mayer equaton, Kapustinskii equation and Kudriavtsev equation. (Data taken from Table 2.). The line is of unit slope. m indicates Eq.2.23, 3}f indicates Born-Mayer equation,q indicates Kapustinskii equation, A indicates Kudriavtsev equation.

42 98 'o E le c tro n ic p o la r iz a b ility ( a ) o in Known R avindra R e f.26 R e f.25 P re sen t study E q.2.48 R e f o <f r~ fa la fa so fa ta so la O o so o A* fa ta r~ fa sf a a st ta ON A* fa <r fa fa 4.39 A- so A- A- ON fa fa A" fa la ON A* A* a t Os SO fa so so fa so in <* so , fa A- O 0.73 I I $ i f! I i»* i I t i i I I i i i l» i *I I l I i i i I t»!i I ta >> 4> H U (si U S3 U. H CU U_ U w CT UJ >Cfr Os T in ra ta la o»»i Ii «l I Table 2.2. L a ttic e e n e rg ie s and o p to -e le c tro n ic p ro p e rtie s o f a lk a li h a lid e s > CP 03 <t cc Q. a> uj a. or uj 3> 3 >> cn Ul <u c «e 03 o_ U (kcal/m ole) C a. (-4o H D W 3 H XX -H 0 <Z Xz S tan d ard v alu e E q P resen t study E q.2.29 E x p tl. d ata R e f.89 P re sen t stu d y E q A "M. t i t» cc oz w u- 03 cr r~ o so fa M3 so <r fa la , a tn Os lx. T3T LiBr H u. z A' fa A- fa <* M u Z 2.98 fa fa fa so r~ M z «Z U- Z so fa so A* ON fa Os SO r- sd KCt U SZ iz ON la RbF in GO fa RbCl RbBr fa <r A* VO fa so so fa 3 QC <r o so ofa <r CsF CsCl fa A* fa CsBr Csl l l I i i f»i l I»I I» l l»l I I i i» li *i i f i ii J» I ii I } I j! t i i ii

43 99 Measurements and correct estimations of these various terms are rather difficult and sometimes unpredictable. So one cannot obtain lattice energies by these potentials in the absence of any of these parameters. Keeping in view the above limitations, the author has proposed a simple of means of obtaining lattice energies for nearly 00 ionic solids from interionic distance. The results in each case are compared with the experimental data. Table 2. presents the lattice energies for alkali halide crystals calculated from equation 2.23 and the experimental values obtained from the Born-Haber cycle. For the sake of comparison, the values of U obtained from other theoretical methods viz. Born-Mayer equation, Bom-Lande equation, Kapustinskii's equation and Kudriavtsev's equation are also included in the same table. To highlight the comparisons made between various theories, a plot (Figure 2.) is drawn between the experimental values and the values obtained from different approaches. A glance at the Figure 2. reveals that the lattice energies calculated in the present study for alkali halides present a much closer agreement with the experimental thermochemical cycle values than the corresponding values obtained by the other theories. The figure also presents an equally good performance by the Born-Mayer equation in predicting the correct values for alkali halides. The average

44 00 percentage deviation between the calculated and the experimental values for the present method is found to be only.7% while it is maximum of 8% in the case of Kudriavtsev's equation. This clearly shows the relative superiority of the author's relation over others' in predicting the accurate values of lattice energies. Equation 2.29 gives the correlation between the lattice energy U and the plasma energy ( ) in the case of alkali halide crystals. The lattice energy values obtained from the rq values are utilized in equation 2.29 to evaluate the plasma energies in. alkali halide crystals and the values are presented in Table 2.2 along with the standard values obtained from the plasma oscillations theory of solids. It is readily seen from the table that there is a good agreement between the predicted and the standard ones. The computed values of plasma energy are further utilized to evaluate some of the important opto-electronic properties viz., the Penn gap (Ep), Fermi energy (Ef), So-parameter and the electronic polarizability (Of) using the appropriate relations as described at length in the previous chapter. It is encouraging to observe that the (X -values tally closely with the corresponding experimental values. This clearly corroborates the validity of our relation in describing the various opto-electronic properties. The present study demonstrates the usefulness of a simple lattice property like the lattice energy in linking with several opto-electronic properties through simple linear relations.

Lattice energy of ionic solids

Lattice energy of ionic solids 1 Lattice energy of ionic solids Interatomic Forces Solids are aggregates of atoms, ions or molecules. The bonding between these particles may be understood in terms of forces that play between them. Attractive

More information

Chapter 11 Intermolecular Forces, Liquids, and Solids

Chapter 11 Intermolecular Forces, Liquids, and Solids Chapter 11 Intermolecular Forces, Liquids, and Solids Dissolution of an ionic compound States of Matter The fundamental difference between states of matter is the distance between particles. States of

More information

Ionic Bond, Latice energy, characteristic of Ionic compounds

Ionic Bond, Latice energy, characteristic of Ionic compounds Ionic Bond, Latice energy, characteristic of Ionic compounds 1. The strong electrostatic attraction between two oppositely charged ions which are formed due to transfer of electrons from one atom to another

More information

E12 UNDERSTANDING CRYSTAL STRUCTURES

E12 UNDERSTANDING CRYSTAL STRUCTURES E1 UNDERSTANDING CRYSTAL STRUCTURES 1 Introduction In this experiment, the structures of many elements and compounds are rationalized using simple packing models. The pre-work revises and extends the material

More information

Chapter 3. Crystal Binding

Chapter 3. Crystal Binding Chapter 3. Crystal Binding Energy of a crystal and crystal binding Cohesive energy of Molecular crystals Ionic crystals Metallic crystals Elasticity What causes matter to exist in three different forms?

More information

Spectroscopic Constants & Potential Energy Function for Diatomic Molecules

Spectroscopic Constants & Potential Energy Function for Diatomic Molecules International Journal Of Computational Engineering Research (ijceronline.com) Vol. 3 Issue. 3 Spectroscopic Constants & Potential Energy Function for Diatomic Molecules 1, Ratikant Thakur and 2, Jagdhar

More information

Chapter 3 (part 3) The Structures of Simple Solids

Chapter 3 (part 3) The Structures of Simple Solids CHM 511 chapter 3 page 1 of 9 Chapter 3 (part 3) The Structures of Simple Solids Rationalizing Structures Ionic radii As noted earlier, a reference value is needed. Usually oxygen is assumed to be 140

More information

Ionic Bonding - Electrostatic Interactions and Polarization

Ionic Bonding - Electrostatic Interactions and Polarization Ionic Bonding - Electrostatic Interactions and Polarization Chemistry 754 Solid State Chemistry Dr. Patrick Woodward Lecture #13 Born-Haber Cycle for NaCl It is energetically unfavorable for Na metal and

More information

Ionic Bonding. Chem

Ionic Bonding. Chem Whereas the term covalent implies sharing of electrons between atoms, the term ionic indicates that electrons are taken from one atom by another. The nature of ionic bonding is very different than that

More information

Inorganic Pharmaceutical Chemistry

Inorganic Pharmaceutical Chemistry Inorganic Pharmaceutical Chemistry Lecture No. 4 Date :25/10 /2012 Dr. Mohammed Hamed --------------------------------------------------------------------------------------------------------------------------------------

More information

Chemistry 101 Chapter 9 CHEMICAL BONDING. Chemical bonds are strong attractive force that exists between the atoms of a substance

Chemistry 101 Chapter 9 CHEMICAL BONDING. Chemical bonds are strong attractive force that exists between the atoms of a substance CHEMICAL BONDING Chemical bonds are strong attractive force that exists between the atoms of a substance Chemical Bonds are commonly classified into 3 types: 1. IONIC BONDING Ionic bonds usually form between

More information

lattice formation from gaseous ions

lattice formation from gaseous ions BORN HABER CYCLES The Born Haber cycles is an adaption of Hess s law to calculate lattice enthalpy from other data The lattice enthalpy cannot be determined directly. We calculate it indirectly by making

More information

Unit 7: Basic Concepts of Chemical Bonding. Chemical Bonds. Lewis Symbols. The Octet Rule. Transition Metal Ions. Ionic Bonding 11/17/15

Unit 7: Basic Concepts of Chemical Bonding. Chemical Bonds. Lewis Symbols. The Octet Rule. Transition Metal Ions. Ionic Bonding 11/17/15 Unit 7: Basic Concepts of Chemical Bonding Topics Covered Chemical bonds Ionic bonds Covalent bonds Bond polarity and electronegativity Lewis structures Exceptions to the octet rule Strength of covalent

More information

Atomic Structure & Interatomic Bonding

Atomic Structure & Interatomic Bonding Atomic Structure & Interatomic Bonding Chapter Outline Review of Atomic Structure Atomic Bonding Atomic Structure Atoms are the smallest structural units of all solids, liquids & gases. Atom: The smallest

More information

Lecture 6 - Bonding in Crystals

Lecture 6 - Bonding in Crystals Lecture 6 onding in Crystals inding in Crystals (Kittel Ch. 3) inding of atoms to form crystals A crystal is a repeated array of atoms Why do they form? What are characteristic bonding mechanisms? How

More information

4/4/2013. Covalent Bonds a bond that results in the sharing of electron pairs between two atoms.

4/4/2013. Covalent Bonds a bond that results in the sharing of electron pairs between two atoms. A chemical bond is a mutual electrical attraction between the nucleus and valence electrons of different atoms that binds the atoms together. Why bond? As independent particles, atoms have a high potential

More information

SOLID STATE CHEMISTRY

SOLID STATE CHEMISTRY SOLID STATE CHEMISTRY Crystal Structure Solids are divided into 2 categories: I. Crystalline possesses rigid and long-range order; its atoms, molecules or ions occupy specific positions, e.g. ice II. Amorphous

More information

"My name is Bond." N2 (Double 07)

My name is Bond. N2 (Double 07) "My name is Bond." N2 (Double 07) "Metallic Bond." Element 3: Lithium [He]2s 1 "My name is Bond." In the last lecture we identified three types of molecular bonding: van der Waals Interactions (Ar) Covalent

More information

The broad topic of physical metallurgy provides a basis that links the structure of materials with their properties, focusing primarily on metals.

The broad topic of physical metallurgy provides a basis that links the structure of materials with their properties, focusing primarily on metals. Physical Metallurgy The broad topic of physical metallurgy provides a basis that links the structure of materials with their properties, focusing primarily on metals. Crystal Binding In our discussions

More information

Chapter 9 Ionic and Covalent Bonding

Chapter 9 Ionic and Covalent Bonding Chem 1045 Prof George W.J. Kenney, Jr General Chemistry by Ebbing and Gammon, 8th Edition Last Update: 06-April-2009 Chapter 9 Ionic and Covalent Bonding These Notes are to SUPPLIMENT the Text, They do

More information

The Nature of the Ionic Bond*

The Nature of the Ionic Bond* Aust. J. Phys., 1976, 29, 39-50 The Nature of the onic Bond* K. P. Thakur Department of Physics, S.P. College, Dumka (S.P.) 814101, Bihar, ndia. Abstract A new model to describe interionic binding in diatomic

More information

CHAPTER-3 CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES OF ELEMENTS

CHAPTER-3 CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES OF ELEMENTS CHAPTER-3 CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES OF ELEMENTS Mandeleev s Periodic Law:- The properties of the elements are the periodic function of their atomic masses. Moseley, the English

More information

Forming Chemical Bonds

Forming Chemical Bonds Forming Chemical Bonds Chemical Bonds Three basic types of bonds 2012 Pearson Education, Inc. Ionic Electrostatic attraction between ions. Covalent Sharing of electrons. Metallic Metal atoms bonded to

More information

DEVELOPMENT OF THE PERIODIC TABLE

DEVELOPMENT OF THE PERIODIC TABLE DEVELOPMENT OF THE PERIODIC TABLE Prior to the 1700s, relatively few element were known, and consisted mostly of metals used for coinage, jewelry and weapons. From early 1700s to mid-1800s, chemists discovered

More information

GHW#3. Chapter 3. Louisiana Tech University, Chemistry 481. POGIL(Process Oriented Guided Inquiry Learning) Exercise on Chapter 3.

GHW#3. Chapter 3. Louisiana Tech University, Chemistry 481. POGIL(Process Oriented Guided Inquiry Learning) Exercise on Chapter 3. GHW#3. Chapter 3. Louisiana Tech University, Chemistry 481. POGIL(Process Oriented Guided Inquiry Learning) Exercise on Chapter 3. Energetics of Ionic Bonding. Why? What are the properties of ionic compounds?

More information

The change in free energy on transferring an ion from a medium of low dielectric constantε1 to one of high dielectric constant ε2:

The change in free energy on transferring an ion from a medium of low dielectric constantε1 to one of high dielectric constant ε2: The Born Energy of an Ion The free energy density of an electric field E arising from a charge is ½(ε 0 ε E 2 ) per unit volume Integrating the energy density of an ion over all of space = Born energy:

More information

Periodicity SL (answers) IB CHEMISTRY SL

Periodicity SL (answers) IB CHEMISTRY SL (answers) IB CHEMISTRY SL Syllabus objectives 3.1 Periodic table Understandings: The periodic table is arranged into four blocks associated with the four sublevels s, p, d, and f. The periodic table consists

More information

CHEMISTRY - CLUTCH CH.9 - BONDING & MOLECULAR STRUCTURE.

CHEMISTRY - CLUTCH CH.9 - BONDING & MOLECULAR STRUCTURE. !! www.clutchprep.com CONCEPT: ATOMIC PROPERTIES AND CHEMICAL BONDS Before we examine the types of chemical bonding, we should ask why atoms bond at all. Generally, the reason is that ionic bonding the

More information

Ionic Bonding and Ionic Compounds

Ionic Bonding and Ionic Compounds Main Ideas Ionic bonds form from attractions between positive and negative ions Differences in attraction strength give ionic and molecular compounds different properties Multiple atoms can bond covalently

More information

100% ionic compounds do not exist but predominantly ionic compounds are formed when metals combine with non-metals.

100% ionic compounds do not exist but predominantly ionic compounds are formed when metals combine with non-metals. 2.21 Ionic Bonding 100% ionic compounds do not exist but predominantly ionic compounds are formed when metals combine with non-metals. Forming ions Metal atoms lose electrons to form +ve ions. Non-metal

More information

Chapter 7. Periodic Properties of the Elements. Lecture Outline

Chapter 7. Periodic Properties of the Elements. Lecture Outline Chapter 7. Periodic Properties of the Elements Periodic Properties of the Elements 1 Lecture Outline 7.1 Development of the Periodic Table The periodic table is the most significant tool that chemists

More information

Atoms, Molecules and Solids (selected topics)

Atoms, Molecules and Solids (selected topics) Atoms, Molecules and Solids (selected topics) Part I: Electronic configurations and transitions Transitions between atomic states (Hydrogen atom) Transition probabilities are different depending on the

More information

15.2 Born-Haber Cycles

15.2 Born-Haber Cycles 15.2 Born-Haber Cycles 15.2.1 - Define and apply the terms lattice enthalpy and electron affinity Lattice Enthalpy The energy required to completely separate one mole of a solid ionic compound into its

More information

Bonding. Each type of bonding gives rise to distinctive physical properties for the substances formed.

Bonding. Each type of bonding gives rise to distinctive physical properties for the substances formed. Bonding History: In 55 BC, the Roman poet and philosopher Lucretius stated that a force of some kind holds atoms together. He wrote that certain atoms when they collide, do not recoil far, being driven

More information

CHEMICAL BONDING. Ionic Bond:

CHEMICAL BONDING. Ionic Bond: Ionic Bond: CHEMICAL BONDING It is formed by the complete transference of one or more electrons from the outermost energy shell (Valency shell) of one atom to the outermost energy shell of the other atom.

More information

Bonding in Solids. What is the chemical bonding? Bond types: Ionic (NaCl vs. TiC?) Covalent Van der Waals Metallic

Bonding in Solids. What is the chemical bonding? Bond types: Ionic (NaCl vs. TiC?) Covalent Van der Waals Metallic Bonding in Solids What is the chemical bonding? Bond types: Ionic (NaCl vs. TiC?) Covalent Van der Waals Metallic 1 Ions and Ionic Radii LiCl 2 Ions (a) Ions are essentially spherical. (b) Ions may be

More information

Unit 4: Presentation A Covalent Bonding. Covalent Bonding. Slide 2 / 36. Slide 1 / 36. Slide 4 / 36. Slide 3 / 36. Slide 6 / 36.

Unit 4: Presentation A Covalent Bonding. Covalent Bonding. Slide 2 / 36. Slide 1 / 36. Slide 4 / 36. Slide 3 / 36. Slide 6 / 36. Slide 1 / 36 New Jersey Center for Teaching and Learning Progressive Science Initiative This material is made freely available at www.njctl.org and is intended for the non-commercial use of students and

More information

CHAPTER 1 Atoms and bonding. Ionic bonding Covalent bonding Metallic bonding van der Waals bonding

CHAPTER 1 Atoms and bonding. Ionic bonding Covalent bonding Metallic bonding van der Waals bonding CHAPTER 1 Atoms and bonding The periodic table Ionic bonding Covalent bonding Metallic bonding van der Waals bonding Atoms and bonding In order to understand the physics of semiconductor (s/c) devices,

More information

ASSOCIATE DEGREE IN ENGINEERING TECHNOLOGY RESIT EXAMINATIONS. SEMESTER 2 July, 2012

ASSOCIATE DEGREE IN ENGINEERING TECHNOLOGY RESIT EXAMINATIONS. SEMESTER 2 July, 2012 ASSOCIATE DEGREE IN ENGINEERING TECHNOLOGY RESIT EXAMINATIONS SEMESTER 2 July, 2012 COURSE NAME: CODE: CHEMISTRY FOR ENGINEEERS CHY-1008 GROUP: ADET 2 DATE: July 2, 2011 TIME: DURATION: 1:00 pm 2 HOURS

More information

HW 2. CHEM 481 Chapters 3 & 5 Chapter 3. Energetics of Ionic Bonding

HW 2. CHEM 481 Chapters 3 & 5 Chapter 3. Energetics of Ionic Bonding HW 2. CHEM 481 Chapters 3 & 5 Chapter 3. Energetics of Ionic Bonding Name: 1. Give coordination number for both anion and cation of the following ionic lattices. a) CsCl Structure: b) Rock Salt Structure:

More information

5.2.1 Answers Lattice Enthalpy 2012

5.2.1 Answers Lattice Enthalpy 2012 5.2.1 Answers Lattice Enthalpy 2012 Introduction In this topic we will construct a Born-Haber cycle (or lattice enthalpy cycle) which allows us to calculate numerical values for processes which occur in

More information

Materials Science and Engineering I

Materials Science and Engineering I Materials Science and Engineering I Chapter Outline Review of Atomic Structure Electrons, Protons, Neutrons, Quantum number of atoms, Electron states, The Periodic Table Atomic Bonding in Solids Bonding

More information

Types of bonding: OVERVIEW

Types of bonding: OVERVIEW 1 of 43 Boardworks Ltd 2009 Types of bonding: OVERVIEW 2 of 43 Boardworks Ltd 2009 There are three types of bond that can occur between atoms: an ionic bond occurs between a metal and non-metal atom (e.g.

More information

15.2 Born-Haber Cycle

15.2 Born-Haber Cycle 15.2 Born-Haber Cycle Our calculations of enthalpies so far have involved covalent substances. Now we need to look at the enthalpy changes involved in the formation of giant ionic lattices. Lattice enthalpy

More information

- intermolecular forces forces that exist between molecules

- intermolecular forces forces that exist between molecules Chapter 11: Intermolecular Forces, Liquids, and Solids - intermolecular forces forces that exist between molecules 11.1 A Molecular Comparison of Liquids and Solids - gases - average kinetic energy of

More information

A) I and III B) I and IV C) II and IV D) II and III E) III 5. Which of the following statements concerning quantum mechanics is/are true?

A) I and III B) I and IV C) II and IV D) II and III E) III 5. Which of the following statements concerning quantum mechanics is/are true? PX0311-0709 1. What is the wavelength of a photon having a frequency of 4.50 10 14 Hz? (, ) A) 667 nm B) 1.50 10 3 nm C) 4.42 10 31 nm D) 0.0895 nm E) 2.98 10 10 nm 2. When a particular metal is illuminated

More information

lectures accompanying the book: Solid State Physics: An Introduction, by Philip ofmann (2nd edition 2015, ISBN-10: 3527412824, ISBN-13: 978-3527412822, Wiley-VC Berlin. www.philiphofmann.net 1 Bonds between

More information

Energetics of Bond Formation

Energetics of Bond Formation BONDING, Part 4 Energetics of Bond Formation 167 Energetics of Covalent Bond Formation 168 1 169 Trends in Bond Energies the more electrons two atoms share, the stronger the covalent bond C C (837 kj)

More information

number. Z eff = Z S S is called the screening constant which represents the portion of the nuclear EXTRA NOTES

number. Z eff = Z S S is called the screening constant which represents the portion of the nuclear EXTRA NOTES EXTRA NOTES 1. Development of the Periodic Table The periodic table is the most significant tool that chemists use for organising and recalling chemical facts. Elements in the same column contain the same

More information

12A Entropy. Entropy change ( S) N Goalby chemrevise.org 1. System and Surroundings

12A Entropy. Entropy change ( S) N Goalby chemrevise.org 1. System and Surroundings 12A Entropy Entropy change ( S) A SPONTANEOUS PROCESS (e.g. diffusion) will proceed on its own without any external influence. A problem with H A reaction that is exothermic will result in products that

More information

Metallic & Ionic Solids. Crystal Lattices. Properties of Solids. Network Solids. Types of Solids. Chapter 13 Solids. Chapter 13

Metallic & Ionic Solids. Crystal Lattices. Properties of Solids. Network Solids. Types of Solids. Chapter 13 Solids. Chapter 13 1 Metallic & Ionic Solids Chapter 13 The Chemistry of Solids Jeffrey Mack California State University, Sacramento Crystal Lattices Properties of Solids Regular 3-D arrangements of equivalent LATTICE POINTS

More information

Chapter 5 Notes Chemistry; The Periodic Law The Periodic Table The periodic table is used to organize the elements in a meaningful way.

Chapter 5 Notes Chemistry; The Periodic Law The Periodic Table The periodic table is used to organize the elements in a meaningful way. Chapter 5 Notes Chemistry; The Periodic Law The Periodic Table The periodic table is used to organize the elements in a meaningful way. As a consequence of this organization, there are periodic properties

More information

Ch 7: Periodic Properties of the Elements

Ch 7: Periodic Properties of the Elements AP Chemistry: Periodic Properties of the Elements Lecture Outline 7.1 Development of the Periodic Table The majority of the elements were discovered between 1735 and 1843. Discovery of new elements in

More information

1.8 Thermodynamics. N Goalby chemrevise.org. Definitions of enthalpy changes

1.8 Thermodynamics. N Goalby chemrevise.org. Definitions of enthalpy changes 1.8 Thermodynamics Definitions of enthalpy changes Enthalpy change of formation The standard enthalpy change of formation of a compound is the energy transferred when 1 mole of the compound is formed from

More information

All chemical bonding is based on the following relationships of electrostatics: 2. Each period on the periodic table

All chemical bonding is based on the following relationships of electrostatics: 2. Each period on the periodic table UNIT VIII ATOMS AND THE PERIODIC TABLE 25 E. Chemical Bonding 1. An ELECTROSTATIC FORCE is All chemical bonding is based on the following relationships of electrostatics: The greater the distance between

More information

Elements react to attain stable (doublet or octet) electronic configurations of the noble gases.

Elements react to attain stable (doublet or octet) electronic configurations of the noble gases. digitalteachers.co.ug Chemical bonding This chapter teaches the different types and names of bonds that exist in substances that keep their constituent particles together. We will understand how these

More information

Cartoon courtesy of NearingZero.net. Chemical Bonding and Molecular Structure

Cartoon courtesy of NearingZero.net. Chemical Bonding and Molecular Structure Cartoon courtesy of NearingZero.net Chemical Bonding and Molecular Structure Big Ideas in Unit 6 How do atoms form chemical bonds? How does the type of a chemical bond influence a compounds physical and

More information

CHEMISTRY The Molecular Nature of Matter and Change

CHEMISTRY The Molecular Nature of Matter and Change CHEMISTRY The Molecular Nature of Matter and Change Third Edition Chapter 12 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 11 INTERMOLECULAR FORCES

More information

UNIT 5.1. Types of bonds

UNIT 5.1. Types of bonds UNIT 5.1 Types of bonds REVIEW OF VALENCE ELECTRONS Valence electrons are electrons in the outmost shell (energy level). They are the electrons available for bonding. Group 1 (alkali metals) have 1 valence

More information

ionic solids Ionic Solids

ionic solids Ionic Solids ionic solids Ionic Solids Properties characteristic of ionic solids low conductivity as solids, high when molten high melting points hard brittle solids soluble in polar solvents high melting Hardness

More information

Metallic and Ionic Structures and Bonding

Metallic and Ionic Structures and Bonding Metallic and Ionic Structures and Bonding Ionic compounds are formed between elements having an electronegativity difference of about 2.0 or greater. Simple ionic compounds are characterized by high melting

More information

Materials 218/UCSB: Class III Cohesion in solids van der Waals, ionic, covalent, metallic

Materials 218/UCSB: Class III Cohesion in solids van der Waals, ionic, covalent, metallic Materials 218/UCSB: Class III Cohesion in solids van der Waals, ionic, covalent, metallic Ram Seshadri (seshadri@mrl.ucsb.edu) Introduction There are four forces in nature. The strong and the weak interactions

More information

CHEMISTRY - TRO 4E CH.9 - CHEMICAL BONDING I: THE LEWIS MODEL

CHEMISTRY - TRO 4E CH.9 - CHEMICAL BONDING I: THE LEWIS MODEL !! www.clutchprep.com CONCEPT: ATOMIC PROPERTIES AND CHEMICAL BONDS Before we examine the types of chemical bonding, we should ask why atoms bond at all. Generally, the reason is that ionic bonding the

More information

Chapter 12. Insert picture from First page of chapter. Intermolecular Forces and the Physical Properties of Liquids and Solids

Chapter 12. Insert picture from First page of chapter. Intermolecular Forces and the Physical Properties of Liquids and Solids Chapter 12 Insert picture from First page of chapter Intermolecular Forces and the Physical Properties of Liquids and Solids Copyright McGraw-Hill 2009 1 12.1 Intermolecular Forces Intermolecular forces

More information

CHEMISTRY - BROWN 13E CH.7 - PERIODIC PROPERTIES OF THE ELEMENTS

CHEMISTRY - BROWN 13E CH.7 - PERIODIC PROPERTIES OF THE ELEMENTS !! www.clutchprep.com CONCEPT: EFFECTIVE NUCLEAR CHARGE & SLATER S RULES When looking at any particular electron within an atom it experiences two major forces. A(n) force from the nucleus and a(n) force

More information

Atomic Structure. Atomic weight = m protons + m neutrons Atomic number (Z) = # of protons Isotope corresponds to # of neutrons

Atomic Structure. Atomic weight = m protons + m neutrons Atomic number (Z) = # of protons Isotope corresponds to # of neutrons Atomic Structure Neutrons: neutral Protons: positive charge (1.6x10 19 C, 1.67x10 27 kg) Electrons: negative charge (1.6x10 19 C, 9.11x10 31 kg) Atomic weight = m protons + m neutrons Atomic number (Z)

More information

Li or Na Li or Be Ar or Kr Al or Si

Li or Na Li or Be Ar or Kr Al or Si Pre- AP Chemistry 11 Atomic Theory V Name: Date: Block: 1. Atomic Radius/Size 2. Ionization Energy 3. Electronegativity 4. Chemical Bonding Atomic Radius Effective Nuclear Charge (Z eff) Ø Net positive

More information

Chapter 11. Intermolecular Forces and Liquids & Solids

Chapter 11. Intermolecular Forces and Liquids & Solids Chapter 11 Intermolecular Forces and Liquids & Solids The Kinetic Molecular Theory of Liquids & Solids Gases vs. Liquids & Solids difference is distance between molecules Liquids Molecules close together;

More information

Inorganic Chemistry I (CH331) Solid-state Chemistry I (Crystal structure) Nattapol Laorodphan (Chulabhorn Building, 4 th Floor)

Inorganic Chemistry I (CH331) Solid-state Chemistry I (Crystal structure) Nattapol Laorodphan (Chulabhorn Building, 4 th Floor) Inorganic Chemistry I (CH331) Solid-state Chemistry I (Crystal structure) Nattapol Laorodphan (Chulabhorn Building, 4 th Floor) 7/2013 N.Laorodphan 1 Text books : 1. D.F. Sheiver, P.W. Atkins & C.H. Langford

More information

Intermolecular Forces and Liquids and Solids. Chapter 11. Copyright The McGraw Hill Companies, Inc. Permission required for

Intermolecular Forces and Liquids and Solids. Chapter 11. Copyright The McGraw Hill Companies, Inc. Permission required for Intermolecular Forces and Liquids and Solids Chapter 11 Copyright The McGraw Hill Companies, Inc. Permission required for 1 A phase is a homogeneous part of the system in contact with other parts of the

More information

Bonding forces and energies Primary interatomic bonds Secondary bonding Molecules

Bonding forces and energies Primary interatomic bonds Secondary bonding Molecules Chapter 2. Atomic structure and interatomic bonding 2.1. Atomic structure 2.1.1.Fundamental concepts 2.1.2. Electrons in atoms 2.1.3. The periodic table 2.2. Atomic bonding in solids 2.2.1. Bonding forces

More information

Atoms & Their Interactions

Atoms & Their Interactions Lecture 2 Atoms & Their Interactions Si: the heart of electronic materials Intel, 300mm Si wafer, 200 μm thick and 48-core CPU ( cloud computing on a chip ) Twin Creeks Technologies, San Jose, Si wafer,

More information

13 Energetics II. Eg. Na (g) Na + (g) + e - ΔH = +550 kj mol -1

13 Energetics II. Eg. Na (g) Na + (g) + e - ΔH = +550 kj mol -1 13 Energetics II First ionisation energy I(1) or IE (1): the energy required to remove one mole of electrons from one mole of the gaseous atoms of an element to 1 mole of gaseous monopositive ions. Eg.

More information

Ø Draw the Bohr Diagrams for the following atoms: Sodium Potassium Rubidium

Ø Draw the Bohr Diagrams for the following atoms: Sodium Potassium Rubidium Chemistry 11 Atomic Theory V Name: Date: Block: 1. Atomic Radius 2. Ionization Energy 3. Electronegativity 4. Chemical Bonding Atomic Radius Periodic Trends Ø As we move across a period or down a chemical

More information

CHAPTER 2. Atomic Structure And Bonding 2-1

CHAPTER 2. Atomic Structure And Bonding 2-1 CHAPTER 2 Atomic Structure And Bonding 2-1 Structure of Atoms ATOM Basic Unit of an Element Diameter : 10 10 m. Neutrally Charged Nucleus Diameter : 10 14 m Accounts for almost all mass Positive Charge

More information

1. Following Dalton s Atomic Theory, 2. In 1869 Russian chemist published a method. of organizing the elements. Mendeleev showed that

1. Following Dalton s Atomic Theory, 2. In 1869 Russian chemist published a method. of organizing the elements. Mendeleev showed that 20 CHEMISTRY 11 D. Organizing the Elements The Periodic Table 1. Following Dalton s Atomic Theory, By 1817, chemists had discovered 52 elements and by 1863 that number had risen to 62. 2. In 1869 Russian

More information

8.1 Early Periodic Tables CHAPTER 8. Modern Periodic Table. Mendeleev s 1871 Table

8.1 Early Periodic Tables CHAPTER 8. Modern Periodic Table. Mendeleev s 1871 Table 8.1 Early Periodic Tables CHAPTER 8 Periodic Relationships Among the Elements 1772: de Morveau table of chemically simple substances 1803: Dalton atomic theory, simple table of atomic masses 1817: Döbreiner's

More information

Chapter Outline Understanding of interatomic bonding is the first step towards understanding/explaining materials properties Review of Atomic

Chapter Outline Understanding of interatomic bonding is the first step towards understanding/explaining materials properties Review of Atomic Chapter Outline Understanding of interatomic bonding is the first step towards understanding/explaining materials properties Review of Atomic Structure: Electrons, Protons, Neutrons, Quantum mechanics

More information

7. How many unpaired electrons are there in an atom of tin in its ground state? 2

7. How many unpaired electrons are there in an atom of tin in its ground state? 2 Name period AP chemistry Unit 2 worksheet 1. List in order of increasing energy: 4f, 6s, 3d,1s,2p 1s, 2p, 6s, 4f 2. Explain why the effective nuclear charge experienced by a 2s electron in boron is greater

More information

Ionic Compounds 1 of 31 Boardworks Ltd 2016

Ionic Compounds 1 of 31 Boardworks Ltd 2016 Ionic Compounds 1 of 31 Boardworks Ltd 2016 Ionic Compounds 2 of 31 Boardworks Ltd 2016 3 of 31 Boardworks Ltd 2016 Elements and compounds Elements are made up of just one type of atom. Some elements exist

More information

WS 1: Ionic Bonds 1. Charge on particle 1= q1 Charge on particle 2 = q2

WS 1: Ionic Bonds 1. Charge on particle 1= q1 Charge on particle 2 = q2 Part I: The Ionic Bonding Model: i WS 1: Ionic Bonds 1 Trends in ionization energies and electron affinities indicate that some elements for ions more readily than others. We know that ions with opposite

More information

Name: Date: Blk: Examine your periodic table to answer these questions and fill-in-the-blanks. Use drawings to support your answers where needed:

Name: Date: Blk: Examine your periodic table to answer these questions and fill-in-the-blanks. Use drawings to support your answers where needed: Name: Date: Blk: NOTES: BONDING Examine your periodic table to answer these questions and fill-in-the-blanks. Use drawings to support your answers where needed: I. IONIC BONDING Ionic bond: formed by the

More information

Full file at

Full file at CHAPTER 2 ATOMIC STRUCTURE AND INTERATOMIC BONDING PROBLEM SOLUTIONS Fundamental Concepts Electrons in Atoms 2.1 Cite the difference between atomic mass and atomic weight. Atomic mass is the mass of an

More information

Chapter 12 INTERMOLECULAR FORCES. Covalent Radius and van der Waals Radius. Intraand. Intermolecular Forces. ½ the distance of non-bonded

Chapter 12 INTERMOLECULAR FORCES. Covalent Radius and van der Waals Radius. Intraand. Intermolecular Forces. ½ the distance of non-bonded Chapter 2 INTERMOLECULAR FORCES Intraand Intermolecular Forces Covalent Radius and van der Waals Radius ½ the distance of bonded ½ the distance of non-bonded Dipole Dipole Interactions Covalent and van

More information

CHAPTER 2 INTERATOMIC FORCES. atoms together in a solid?

CHAPTER 2 INTERATOMIC FORCES. atoms together in a solid? CHAPTER 2 INTERATOMIC FORCES What kind of force holds the atoms together in a solid? Interatomic Binding All of the mechanisms which cause bonding between the atoms derive from electrostatic interaction

More information

6.3 Periodic Trends > Chapter 6 The Periodic Table. 6.3 Periodic Trends. 6.1 Organizing the Elements. 6.2 Classifying the Elements

6.3 Periodic Trends > Chapter 6 The Periodic Table. 6.3 Periodic Trends. 6.1 Organizing the Elements. 6.2 Classifying the Elements 1 63 Periodic Trends > Chapter 6 The Periodic Table 61 Organizing the Elements 62 Classifying the Elements 63 Periodic Trends 2 63 Periodic Trends > CHEMISTRY & YOU How are trends in the weather similar

More information

Trends in Atomic Size. What are the trends among the elements for atomic size? The distances between atoms in a molecule are extremely small.

Trends in Atomic Size. What are the trends among the elements for atomic size? The distances between atoms in a molecule are extremely small. 63 Periodic Trends > 63 Periodic Trends > CHEMISTRY & YOU Chapter 6 The Periodic Table 61 Organizing the Elements 62 Classifying the Elements 63 Periodic Trends How are trends in the weather similar to

More information

Midterm I Results. Mean: 35.5 (out of 100 pts) Median: 33 Mode: 25 Max: 104 Min: 2 SD: 18. Compare to: 2013 Mean: 59% 2014 Mean: 51%??

Midterm I Results. Mean: 35.5 (out of 100 pts) Median: 33 Mode: 25 Max: 104 Min: 2 SD: 18. Compare to: 2013 Mean: 59% 2014 Mean: 51%?? Midterm I Results Mean: 35.5 (out of 100 pts) Median: 33 Mode: 25 Max: 104 Min: 2 SD: 18 Compare to: 2013 Mean: 59% 2014 Mean: 51%?? Crystal Thermodynamics and Electronic Structure Chapter 7 Monday, October

More information

Types of Bonding : Ionic Compounds. Types of Bonding : Ionic Compounds

Types of Bonding : Ionic Compounds. Types of Bonding : Ionic Compounds Types of Bonding : Ionic Compounds Ionic bonding involves the complete TRANSFER of electrons from one atom to another. Usually observed when a metal bonds to a nonmetal. - - - - - - + + + + + + + + + +

More information

(03) WMP/Jun10/CHEM4

(03) WMP/Jun10/CHEM4 Thermodynamics 3 Section A Answer all questions in the spaces provided. 1 A reaction mechanism is a series of steps by which an overall reaction may proceed. The reactions occurring in these steps may

More information

Chapter Outline Understanding of interatomic bonding is the first step towards understanding/explaining materials properties Review of Atomic

Chapter Outline Understanding of interatomic bonding is the first step towards understanding/explaining materials properties Review of Atomic Chapter Outline Understanding of interatomic bonding is the first step towards understanding/explaining materials properties Review of Atomic Structure: Electrons, Protons, Neutrons, Quantum mechanics

More information

- Some properties of elements can be related to their positions on the periodic table.

- Some properties of elements can be related to their positions on the periodic table. 186 PERIODIC TRENDS - Some properties of elements can be related to their positions on the periodic table. ATOMIC RADIUS - The distance between the nucleus of the atoms and the outermost shell of the electron

More information

1 P a g e h t t p s : / / w w w. c i e n o t e s. c o m / Chemistry (A-level)

1 P a g e h t t p s : / / w w w. c i e n o t e s. c o m / Chemistry (A-level) 1 P a g e h t t p s : / / w w w. c i e n o t e s. c o m / Lattice energy (Chapter 19 TB) Chemistry (A-level) Lattice energy is the enthalpy change when 1 mole of an ionic compound is formed from its gaseous

More information

Professor K. Section 8 Electron Configuration Periodic Table

Professor K. Section 8 Electron Configuration Periodic Table Professor K Section 8 Electron Configuration Periodic Table Schrödinger Cannot be solved for multielectron atoms We must assume the orbitals are all hydrogen-like Differences In the H atom, all subshells

More information

Ch. 7- Periodic Properties of the Elements

Ch. 7- Periodic Properties of the Elements Ch. 7- Periodic Properties of the Elements 7.1 Introduction A. The periodic nature of the periodic table arises from repeating patterns in the electron configurations of the elements. B. Elements in the

More information

CHAPTER-9 NCERT SOLUTIONS

CHAPTER-9 NCERT SOLUTIONS CHAPTER-9 NCERT SOLUTIONS Question 9.1: Justify the position of hydrogen in the periodic table on the basis of its electronic configuration. Hydrogen is the first element of the periodic table. Its electronic

More information

Covalent Bonding. a. O b. Mg c. Ar d. C. a. K b. N c. Cl d. B

Covalent Bonding. a. O b. Mg c. Ar d. C. a. K b. N c. Cl d. B Covalent Bonding 1. Obtain the number of valence electrons for each of the following atoms from its group number and draw the correct Electron Dot Notation (a.k.a. Lewis Dot Structures). a. K b. N c. Cl

More information

Cartoon courtesy of NearingZero.net. Chemical Bonding and Molecular Structure

Cartoon courtesy of NearingZero.net. Chemical Bonding and Molecular Structure Cartoon courtesy of NearingZero.net Chemical Bonding and Molecular Structure Chemical Bonds Forces that hold groups of atoms together and make them function as a unit. 3 Major Types: Ionic bonds transfer

More information

Intermolecular Forces and Liquids and Solids

Intermolecular Forces and Liquids and Solids Intermolecular Forces and Liquids and Solids Chapter 11 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. A phase is a homogeneous part of the system in contact

More information