Contents. Theory Exercise Exercise Exercise Exercise Answer Key 28-29

Transcription

1 ATOMIC STRUCTURE Topic Contents Page No. Teory 0-04 Exercise Exercise Exercise Exercise Answer Key 8-9 Syllabus Bor model, spectrum of ydrogen atom, quantum numbers; Wave-particle duality, de-broglie ypotesis; Uncertainty principle; Qualitative quantum mecanical picture of ydrogen atom, sapes of s, p and d orbitals; Electronic configurations of elements (up to atomic number 36); Aufbau principle; Pauli s exclusion principle and Hund s rule.. Name : Contact No.

2 ATOMIC STRUCTURE KEY CONCEPTS Electromagnetic Wave Radiation : Te oscillating electrical/magnetic field are electromagnetic radiations. Experimentally, te direction of oscillations of electrical and magnetic field are prependicular to eac oter. Wavelengt () : Wavelengt of a wave is defined as te distance between any two consecutive crests or trougs. It is represented by (lambda) and is expressed in Å or m or cm or nm (nanometer) or pm (picometer). Å = 0 8 cm = 0 0 m nm = 0 9 m, pm = 0 m Frequency () : Frequency of a wave is defined as te number of waves passing troug a point in one second. It is represented by (nu) and is expressed in Hertz (Hz) or cycles/sec or simply sec or s. Hz = cycle/sec v = Quantum Teory of Ligt : Te smallest quantity of energy tat can be emitted or absorbed in te form of electromagnetic radiation is called as quantum of ligt. = 6.66 x 0 34 J-Sec ( - Planck const.) E 0 = c (c - speed of ligt) ( - wavelengt) Order of magnitude of E o = 0 = 0 6 J 0 One Electron Volt (e.v.) : Energy gained by an electron wen it is accelerated from rest troug a potential difference of volt. ev =.6 x 0 9 J For eac metal, tere is a caracteristic minimum frequency, 0 (also known as tresold frequency) below wic potoelectric effect is not observed. At a frequency > 0, te ejected electrons come out wit certain kinetic energy. Te kinetic energies of tese electrons increase wit te increase of frequency of te ligt used. = 0 + me Radius of te Bor s orbit : r = n 4 mkze were ; = erg. sec. r n = 0.59 x n Z Å Velocity of an Electron in Bor s Orbit : v = Ze K n v n =.8 x 0 6 x n Z m/sec ; v Z ; v n Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE #

3 Energy of an Electron : T.E. = KZe r T.E. = E n = me 4 k z n... (iv) Z E n = 3.6 n ev / atom n T.E. ; Z T.E. = Z n J/atom Relation Between P. E., K. E. & T. E. : P.E. T.E. K.E. Definition Valid for Single Electron System : (i) Ground state : Lowest energy state of any atom or ion is called ground state of te atom It is n =. Ground state energy of H atom = 3.6 ev Ground state energy of He + on = 54.4 ev (ii) Excited State : States of atom oter tan te ground state are called excited states : n = first excited state n = 3 second excited state n = 4 tird excited state n = n + n t excited state (iii) Ionisation energy (IE) : Minimum energy required to move an electron from ground state to n = is called ionisation energy of te atom or ion. onisation energy of H atom = 3.6 ev onisation energy of He + ion = 54.4 ev onisation energy of Li + ion =.4 ev Line Spectrum of Hydrogen : Wave number, = = RZ n n R = Rydberg constant = m ; R ~. 0 7 m ; R = 3.6eV c ; R c = 3.6 ev Spectra lines of Hydrogen Atom : Lyman Series It is first spectral series of H. It was found out in ultraviolet region in 898 by Lyman. It s value of n = and n =,3,4 were n is ground state and n is called excited state of electron present in a H - atom. Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE #

4 Balmer Series : It is te second series of H-spectrum. It was found out in 89 in visible region by Balmer. It s value of n = and n = 3,4,5,... Pascen Series : It is te tird series of H - spectrum. It was found out in infrared region by Pascen. It s value of n = 3 and n = 4,5,6... Brackett Series : It is fourt series of H - spectrum. It was found out in infrared region by Brackett. It s value of n = 4 and n = 5,6,7... Pfund Series : It is fift series of H- spectrum. It was found out in infrared region by Pfund. It s value of n = 5 and n = 6,7,8... were n is ground state and n is excited state. Humpry Series : It is te sixt series of H - spectrum. It was found out in infrared region by Humpry. It s value of n = 6 and n = 7, 8, 9... Wave Mecanical Model of Atom : Dual nature of electron (de-broglie Hypotesis): = mc = m(k.e.) = m(q.v) Heisenberg s Uncertainty Principle : Te exact position and momentum of a fast moving particle cannot be calculated precisely at te same moment of time. If x is te error in te measurement of position of te particle and if p is te error in te measurement of momentum of te particle, ten: x. p or x. (mv) 4 4 Scrodinger wave equation : x + y + z 8 m + (E - V) = 0 were x, y and z are tree space coordinates m is te mass of electron is planck s constant E is total energy V is potential energy of e is te amplitude of wave also called wave function Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 3

5 Quantum Numbers : Te set of four numbers required to define an electron completely in an atom are called quantum numbers. Te first tree ave been derived from Scrodinger wave equation. (i) Principal quantum number (n) : (Proposed by Bor) It describes te size of te electron wave and te total energy of te electron. It as integral values,, 3, 4..., etc., and is denoted by K, L, M, N...., etc. Number of subsell present in n t sell = n n subsell s s, p 3 s, p, d 4 s, p, d, f Number of orbitals present in n t sell = n. Te maximum number of electrons wic can be present in a principal energy sell is equal to n. No energy sell in te atoms of known elements possesses more tan 3 electrons. Angular momentum of any orbit = n (ii) Azimutal quantum number () : (Proposed by Sommerfield) It describes te sape of electron cloud and te number of subsells in a sell. It can ave values from 0 to (n ) value of 0 s p d 3 f subsell Number of orbitals in a subsell = + Maximum number of electrons in particular subsell = ( + ) Orbital angular momentum L = ( ) = ( ) i.e. Orbital angular momentum of s orbital = 0, Orbital angular momentum of p orbital =, Orbital angular momentum of d orbital = 3 (iii) Magnetic quantum number (m) : (Proposed by Linde) It describes te orientations of te subsells. It can ave values from to + including zero, i.e., total ( + ) values. Eac value corresponds to an orbital. s-subsell as one orbital, p-subsell tree orbitals (p x, p y and p z ), d-subsell five orbitals ( dxy,dyz,dzx,d,d ) and f-subsell as seven orbitals. Te total number of orbitals present in a main energy level is n. (iv) Spin quantum number (s) : (Proposed by Samuel Goldsmit & Ulenbeck) It describes te spin of te electron. It as values +/ and /. signifies clockwise spinning and anticlockwise spinning. Spin magnetic moment s = electrons) e mc It represents te value of spin angular momentum wic is equal to x s(s ) or = n(n ) B.M. (n = no. of unpaired y z s(s ) Maximum spin of atom = x No. of unpaired electron. Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 4

6 PART - I : OBJECTIVE QUESTIONS * Marked Questions are aving more tan one correct option. Section (A) : Nucleus, Plancks Quantum Teory, Potoelectric effect A-. Te study of catode rays (i.e. electronic discarge troug gases) sows tat - (A) Alpa particles are eavier tan protons (B) All forms of matter contain electrons (C) All nuclei contain protons (D) e/m is constant A-. Proton is - (A) Nucleus of deuterium (C) Ionised ydrogen atom (B) Ionised ydrogen molecule (D) An -particle A-3. Wic is not deflected by magnetic field - (A) Neutron (B) Positron (C) Proton (D) Electron A-4. Te ratio of te "e/m" (specific carge) values of a electron and an -particle is - (A) : (B) : (C) : (D) None of tese A-5. Te element aving no neutron in te nucleus of its atom is (A) Hydrogen (B) Nitrogen (C) Helium (D) Boron A-6. Catode rays are - (A) Electromagnetic waves (C) Stream of -particles (B) Radiations (D) Stream of electrons A-7.* Wic of te following is iso-electronic wit neon? (A) O (B) F (C) Mg (D) Na 64 A-8. Te approximate size of te nucleus of 8 Ni is : (A) 3 fm (B) 4 fm (C) 5 fm (D) fm A-9. Te value of Planck s constant is Js. Te velocity of ligt is m/sec. Wic value is closest to te wavelengt of a quantum of ligt wit frequency of sec? (A) m (B) m (C) m (D) 0 5 m A-0. According to Dalton s atomic teory, an atom can (A) Be created (B) Be destroyed (C) Neiter be created nor destroyed (D) None A-. Ruterford s experiment on scattering of alpa particles sowed for te first time tat atom as - (A) Electrons (B) Protons (C) Nucleus (D) Neutrons A-. - particles are represented by (A) Litium atoms (B) Helium nuclei (C) Hydrogen nucleus (D) None of tese A-3. Te MRI (magentic resonance imaging) body scanners used in ospitals operate wit 400 MHz radio frequency energy. Te wavelengt corresponding to tis radio frequency is (A) 0.75 m (B) 0.75 cm (C).5 m (D) cm Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 5

7 A-4. Electromagnetic radiations of wavelengt 4 nm is just sufficient to ionise Sodium atom. Ten te ionisation energy of Sodium in kj mole - is. (A) (B) 400 (C) 47 (D) 600 A-5. Ligt of wavelengt falls on metal aving work function c/ 0. Potoelectric effect will take place only if : (A) 0 (B) 0 (C) 0 (D) 0 / A-6. Poton of wic ligt as maximum energy : (A) red (B) blue (C) violet (D) green A-7. Te ratio of te energy of a poton of 000 Å wavelengt radiation to tat of 4000 Å radiation is (A) / 4 (B) 4 (C) / (D) A-8. A poton of energy is absorbed by a free electron of a metal aving work function w <. Ten : (A) Te electron is sure to come out (B) Te electron is sure to come out wit a kinetic energy ( w) (C) Eiter te electron does not come out or it comes wit a kinetic energy ( w) (D) It may come out wit a kinetic energy less tan ( w) A-9. A bulb of 40 W is producing a ligt of wavelengt 60 nm wit 80% of efficiency ten te number of potons emitted by te bulb in 0 seconds are (ev = J, c = 400 ev Å) (A) 0 8 (B) 0 8 (C) 0 (D) 0 Section : (B) : Bor Model B-. Te sortest wavelengt of He atom in Balmer series is x, ten longest wavelengt in te Pascen series of Li + is (A) 36x 5 (B) 6x 7 9x (C) 5 B-. Correct order of radius of te st orbit of H, He +, Li +, Be 3+ is : (A) H > He + > Li + > Be 3+ (B) Be 3+ > Li + > He + > H (C) He + > Be 3+ > Li + > H (D) He + > H > Li + > Be 3+ 5x (D) 9 B-3. B-4. B-5. Wic electronic level would allow te ydrogen atom to absorb a poton but not to emit a poton (A) 3 (B) (C) 4 (D) Te tird line in Balmer series corresponds to an electronic transition between wic Bor s orbits in ydrogen (A) 5 3 (B) 5 (C) 4 3 (D) 4 Wat is likely to be orbit number for a circular orbit of diameter 0 nm of te ydrogen atom if we assume Bor orbit to be te same as tat represented by te principal quantum number? (A) 0 (B) 4 (C) (D) 6 B-6. If velocity of an electron in orbit of H atom is V, wat will be te velocity of electron in 3 rd orbit of Li + (A) V (B) V/3 (C) 3 V (D) 9 V B-7. Te energy of electron in first Bor s orbit of H-atom is 3.6 ev. Wat will be its potential energy in n = 4 t orbit - (A) 3.6 ev (B) 3.4 ev (C) 0.85 ev (D).70 ev B-8. If te value of E n = 78.4 kcal/mole, te order of te orbit in ydrogen atom is : (A) 4 (B) 3 (C) (D) Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 6

8 B-9. B-0. B-. B-. B-3. Te frequency of line spectrum of sodium is 5.09 x 0 4 sec. Its wave lengt (in nm) will be- [c = m/sec]- (A) 50 nm (B) 40 nm (C) 589 nm (D) 6 nm Te species wic as its fift ionisation potential equal to 340 V is (A) B + (B) C + (C) B (D) C Matc te following (A) Energy of ground state of He + (i) ev (B) Potential energy of orbit of H-atom (ii) 7. ev (C) Kinetic energy of excited state of He + (iii) V (D) Ionisation potential of He + (iv) 54.4 ev (A) A (i), B (ii), C (iii), D (iv) (B) A (iv), B (iii), C (ii), D (i) (C) A (iv), B (ii), C (i), D (iii) (D) A (ii), B (iii), C (i), D (iv) In a certain electronic transition in te ydrogen atoms from an initial state (A) to a final state (B), te difference in te orbital radius (r r ) is 4 times te first Bor radius. Identify te transition. (A) 5 (B) 5 (C) 8 3 (D) 6 5 S : Bor model is applicable for Be + ion. S : Total energy coming out of any ligt source is integral multiple of energy of one poton. S 3 : Number of waves present in unit lengt is wave number. S 4 : e/m ratio in catode ray experiment is independent of te nature of te gas. (A) F F T T (B) T T F F (C) F T T T (D) T F F F B-4. On Bor s stationary orbits - (A) Electrons do not move (C) Energy of te electron remains constant (B) Electrons move emitting radiations (D) Angular momentum of te electron is / B-5. Te value of Bor radius of ydrogen atom is - (A) 0.59x 0 7 cm (B) 0.59x 0-8 cm (C) 0.59x 0-9 cm (D) 0.59x 0 0 cm B-6. On te basis of Bor s model, te radius of te 3rd orbit is - (A) Equal to te radius of first orbit (B)Tree times te radius of first orbit (C) Five times te radius of first orbit (D) Nine time te radius of first orbit B-7. B-8. Supposing te energy of fourt sell for ydrogen atom is - 50 a.u. (arbitrary unit). Wat would be its ionization potential - (A) 50 (B) 800 (C) 5.4 (D) 0.8 Supposing te ionization energy of ydrogen atom is 640 ev. Point out te main sell aving energy equal to 40 ev - (A) n = (B) n = 3 (C) n = 4 (D) n = 5 B-9. Ionization energy for ydrogen atom in ergs, Joules and ev respectively is - (A).8 x 0, 8 x 0 0, 3.6 (B) 3.6 x 8 x 0 0,.8 x 0 3 (C).8 x 0 0, 3.6,.8 x 0 3 (D).8 x 0 3, 3.6,.8 x 0 0 B-0. For ionising an excited ydrogen atom, te energy required in ev will be - (A) 3.4 or less (B) More tan 3.6 (C) Little less tan 3.6 (D) 3.6 B-. A gas absorbs a poton of 300 nm and ten re-emitts two potons. One poton as a wavelengt 600 nm. Te wavelengt of second poton is - (A) 300 nm (B) 400 nm (C) 500 nm (D) 600 nm Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 7

9 B-. B-3. Te ratio of difference in wavelengts of st and nd lines of Lyman series in H like atom to difference in wavelengt for nd and 3 rd lines of same series is: (A).5 : (B) 3.5 : (C) 4.5 : (D) 5.5 : If radius of second stationary orbit (in Bor's atom) is R. Ten radius of tird orbit will be (A) R/3 (B) 9R (C) R/9 (D).5R B-4. Te velocity of an electron in te tird orbit of ydrogen atom - (A) 7.8 x0 7 cm sec (B) 7.08 x 0 7 cm sec (C) 7.38 x 0 7 cm sec (D) 7.48 x0 7 cm sec B-5. Te ionization energy of a ydrogen atom is 3.6eV. Te energy of te tird-lowest electronic level in doubly ionized litium (Z = 3) is - (A) 8.7 ev (B) 54.4 ev (C).4 ev (D) 3.6 ev B-6. Te momentum of a poton wit energy 0 ev is - (A) 0.66 x 0 7 Kg m sec (B) 0.55 x 0 7 Kg m sec (C) 0.60 x 0 7 Kg m sec (D) 0.80 x 0 7 Kg m sec B-7. B-8. Te energy of ydrogen atom in its ground state is 3.6 ev. Te energy of te level corresponding to n = 5 is: (A) 0.54 ev (B) 5.40 ev (C) 0.85 ev (D).7 ev Tree energy levels P, Q, R of a certain atom are suc tat E P < E Q < E R. If, and 3 are te wave lengt of radiation corresponding to transition R Q ; Q P and R P respectively. Te correct relationsip between, and 3 is (A) + = 3 (B) 3 (C) 3 = (D) 3 Section : (C) : Spectrum/Spectral lines C-. Te wavelengt of a spectral line for an electronic transition is inversely proportional to : (A) number of electrons undergoing transition (B) te nuclear carge of te atom (C) te velocity of an electron undergoing transition (D) te difference in te energy involved in te transition C-. No. of visible lines wen an electron returns from 5t orbit to ground state in H spectrum : (A) 5 (B) 4 (C) 3 (D) 0 C-3. C-4. C-5. C-6. Number of possible spectral lines wic may be emitted in bracket series in H atom, if electrons present in 9 t excited level returns to ground level, are (A) (B) 6 (C) 45 (D) 5 Te ratio of wave lengt of poton corresponding to te -line of Lyman series in H-atom and -line of Balmer series in He + is (A) : (B) : (C) : 4 (D) 3 : 6 Total no. of lines in Lyman series of H spectrum will be (were n = no. of orbits) (A) n (B) n (C) n (D) n (n + ) Te difference between te wave number of st line of Balmer series and last line of pascen series for Li + ion is : R (A) 36 5R (B) 36 (C) 4R (D) 4 R Pysical & Inorganic By A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 8 B.Tec. IIT Deli

10 C-7. Te wave number of te first line of Balmer series of ydrogen is 500 cm. Te wave number of te first Balmer line of Li + ion is- (A) 500cm (B) cm (C) cm (D) cm C-8. Suppose tat a ypotetical atom gives a red, green, blue and violet line spectrum. Wic jump according to figure would give off te red spectral line. (A) 3 (B) (C) 4 (D) 3 C-9. Te wavelengt of te tird line of te Balmer series for a ydrogen atom is - (A) 00R H (B) 00 R H R H (C) 00 (D) 00R H C-0. C-. Wave number of a spectral line for a given transition is x cm for He +, ten its value for Be 3+ for te same transition is - (A) 4x cm (B) x cm (C) x/4 cm (D) x cm Wat is te cange in te orbit radius wen te electron in te ydrogen atom (Bor model) undergoes te first Pascen transition - (A) 4.3 x 0 0 m (B) 0.35 x 0 0 m (C) 3.7 x 0 0 m (D).587 x 0 0 m C-. Wave-lengt of te first line of Pascen Series ydrogen spectrum is - (R = cm ) - (A) 8750 (Å) (B) 854 (Å) (C) 345 (Å) (D) 643 (Å) C-3. Te longest wavelengt of He + in Pascen series is "m", ten sortest wavelengt of Be +3 in Pascen series is (in terms of m) : (A) m (B) m (C) m (D) m C-4. If te sortest wavelengt of H atom in Lyman series is x, ten longest wavelengt in Balmer series of He + is - (A) 9 x 5 (B) 36 x 5 (C) x 4 (D) 5 x 9 C-5. A poton was absorbed by a ydrogen atom in its ground state and te electron was promoted to te fift orbit. Wen te excited atom returned to its ground state, visible and oter quanta were emitted. Oter quanta are - (A) (B) 5 (C) 3 (D) 4 C-6. In a sample of H-atom electrons make transition from 5 t excited state to ground state, producing all possible types of potons, ten number of lines in infrared region are (A) 4 (B) 5 (C) 6 (D) 3 Pysical & Inorganic By A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 9 B.Tec. IIT Deli

11 Section : (D) Debroglies ypotesis and Heisenbergs Uncertainty principle D-. An -particle is accelerated troug a potential difference of V volts from rest. Te de-broglie s wavelengt associated wit it is (A) 50 Å V (B) 0.86 Å V (C) 0.0 Å V (D) Å V D-. de-broglie wavelengt of electron in second orbit of Li + ion will be equal to de-broglie of wavelengt of electron in (A) n = 3 of H-atom (B) n = 4 of C 5+ ion (C) n = 6 of Be 3+ ion (D) n = 3 of He + ion D-3. A ball as a mass of 0. kg its velocity is 40 m/s, find out de Broglie wave lengt - (A).66 x 0 34 m (B) x 0 34 m (C) 3 x 0 34 m (D) m D-4. If te uncertainty of position for an electron is zero, wat is te uncertainty of te momentum- (A) Zero (B) (C) (D) Infinite D-5. In an electron microscope, electron are accelerated to great velocities. Calculate te wavelengt of an electron travelling wit a velocity of 7.0 megameters per second. Te mass of an electron is g - (A) m (B) m (C).0 m (D) m D-6. Wat possibly can be te ratio of te de Broglie wavelengts for two electrons eac aving zero initial energy and accelerated troug 50 volts and 00 volts? (A) 3 : 0 (B) 0 : 3 (C) : (D) : D-7. In H-atom, if x is te radius of te first Bor orbit, de Broglie wavelengt of an electron in 3 rd orbit is: (A) 3 x (B) 6 x (C) 9 x (D) x D-8. Wic of te following is te most correct expression for Heisenberg's uncertainty principle (A) x. p (B) x. p 4 4 (C) x. p (D) 4 x. v = 4 D-9. A 00g cricket ball is trown wit a speed of 3.0 x 0 3 cm sec. Wat will be its de Broglie s wavelengt - [ = 6.6 x 0 7 g cm sec ] (A). x 0 3 cm (B). x 0 3 cm (C) 0.55 x 0 3 cm (D).0 x 0 3 cm D-0. Wic is te de-broglie equation - (A) = p (B) = p (C) = p (D) = p + D-. Velocity of elium atom at 300 K is.40 x 0 meter per sec. Wat is its wave lengt - (mass number of elium is 4) (A) 0.46 nm (B) 0.83 nm (C) 803 Å (D) 8000Å Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 0

12 Section (E). Quantum teory E-. An electron as a spin quantum number + / and a magnetic quantum number. It cannot be present in - (A) d-orbital (B) f-orbital (C) s-orbital (D) p-orbital E-. If te electronic structure of oxygen atom is written as s, s it would violate - (A) Hund s rule (C) Bot Hund s and Pauli s principles (B) Paulis exclusion principle (D) None of tese E-3. Te d-subsell is - (A) 5 - Fold degenerate (B) 3-Fold degenerate (C) 7-Fold degenerate (D) Non- degenerate E-4. Te energy of an electron of p y orbital is - (A) Greater tan p x orbital (C) Equal to s orbital (B) Less tan p z orbital (D) Same as tat of p x and p z orbitals E-5. In wic of te following pairs is te probability of finding te electron in xy-plane zero for bot orbitals? (A) 3 d yz,4d x y (B) p z, dz (C) 4d zx, 3p z (D) All of tese E-6. Te number of unpaired electrons in carbon atom is - (A) (B) 4 (C) (D) 3 E-7. Wen 4 d orbital is complete, te newly entering electrons goes in to - (A) 5f (B) 5s (C) 5p (D) 6d Orbital E-8. Wic electronic level would allow te ydrogen atom to absorb a poton but not to emit a poton (A) 3s (B) p (C) s (D) s E-9. Te orbital diagram in wic Aufbau principle is violated is - (A) s p (B) (C) (D) E-0. Te above configuration is not correct as it violates - (A) Only Hund s rule (B) Only Pauli s exclusion principle (C) (n + l) rule (D) (Hund + Pauli) rule E-. d 6 configuration will result in total spin of - (A) 3/ (B) / (C) (D) Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE #

13 PART - II : MISCELLANEOUS QUESTIONS Compreensions Type Compreension # Te only electron in te ydrogen atom resides under ordinary conditions on te first orbit. Wen energy is supplied, te electron moves to iger energy sells depending on te amount of energy absorbed. Wen tis electron returns to any of te lower energy sells, it emits energy. Lyman series is formed wen te electron returns to te lowest energy state wile Balmer series is formed wen te electron returns to second energy sell. Similarly, Pascen, Brackett and pfund series are formed wen electron returns to te tird, fourt and fift energy sells from iger energy sells respectively. Tus, te different spectral lines in te spectra of atoms correspond to different transitions of electrons from iger energy levels to lower energy levels.. If te sortest wavelengt of H atom in Lyman series is x, ten longest wavelengt in Balmer series of He + is : (A) 9 x 5 (B) 36 x 5. Te ratio of te number of spectral lines obtained wen an electron jumps from 7t level to ground state to 6t level to 3rd level. (A) 7 (B) 3.5 (C).5 (D) 0 3. In ydrogen atom wic of te following transitions sould be associated wit igest absorption of energy? (A) n = to n = 4 (B) n = to n = 3 (C) n = 4 to n = (D) n = 3 to n = Compreension # (C) Te Frenc pysicist Louis de Broglie in 94 postulated tat matter, like radiation, sould exibit a dual beaviour. He proposed te following relationsip between te wavelengt of a material particle, its linear momentum p and planck constant = p = mv Te de-broglie relation implies tat t wavelengt of a particle sould decreases as its velocity increase. It also implies tat for a given velocity eavier particles sould ave sorter wavelengt tan ligter particles. Te waves associated wit particles in motion are called matter waves or de Broglie waves. Tese waves differ from te electromagnetic waves as tey (i) ave lower velocities (ii) ave no electrical and magnetic fields and (iii) are not emitted by te particle under consideration. Te experimental confirmation of te de Broglie relation was obtained wen Devisson and Gerner, in 97, observed tat a beam of electron is diffracted by a nickel crystal. As diffraction is a caracteristic property of waves, ence te beam of electron beaves as a wave, as proposed by de Broglie. Warner Heisenberg considered te limits of ow precisely we can measure properties of an electron or oter microscopic particle like electron. He determined tat tere is a fundamental limit of ow closely we can measure bot positon and momentum. Te more accurately we measure te momentum of a particle, te les accurately we can determine its position. Te converse is also true. Tis is summed up in wat we now call te Heisenberg uncertainty principle. It is impossible to determine simultaneously and precisely bot te momentum and position of a particle. Te product of uncertainty in te position, x 4 (D) 5 x 9 x and te uncetainty in te momentum (mv) must be greater tan or equal to Pysical & Inorganic By B.Tec. IIT Deli x (mv) 4 A-479 Indra viar, kota P () () Organic Cemistry By i.e. 4 ATOMIC STRUCTURE #

14 4. If te uncertainty in velocity and position is same, ten te uncertainity in momentum will be: (A) m 4 (B) m 4 (C) 4m (D) m 4 5. Two particles A and B are in motion. If te wavelengt associated wit te particle A is m, te wavelengt of particles B aving momentum alf of A is- (A) m (B) m (C) m (D) m 6. Te uncertainty in te position of an electron (mass = g) moving wit a velocity of cm s accurate upto 0.0% will be (A).9 cm (B) cm (C) 0.75 cm (D) 3.84cm Compreension # 3 de Broglie proposed dual nature for electron by putting is famous equation n proposed uncertainty principle as p. x n. Later on Heisenburg mu. On te contrary particle nature of electron was establised on te basis of potoelectric effect. Wen a poton strikes te metal surface, it gives up its energy to te electron. Part of tis energy (saw W) is used by te electrons to escape from te metal and te remaining imparts te kinetic energy ( mu ) to te potoelectron. Te potential applied on te surface to reduce te velocity of potoelectron to zero is known as stopping potential. 7. Te wavelengt of elium atom wose speed is equal to its rms speed at 7ºC : (A) m 0 (B) m (C) m (D) 6.80 m 8. Wit wat potential sould a beam of electron be accelerated so tat its wavelengt becomes equal to.54 A : (A) 63.3V (B) 6.33V (C) 633V (D) None of tese 9. Te wavelengt of a golf ball weiging 00g and moving at a speed of 5m/r is of te order (A) 0 0 m (B) 0 0 m (C) 30 0 m 40 (D) 0 m Compreension # 4 Te beaviour of an electron in an atom is described matematically by a wave function, or orbital. It turns out tat eac wave function contains tree variables, called quantum numbers, wic are represented as n, l and m. Tese quantum numbers describe te energy level of an orbital and define te sape and orientation of te region in space were te electron will be found. 0. Wic quantum number determines orientation of te electron? (A) Principal (B) Secondary (C) Magnetic (D) Spin. Radial nodes are maximum in (A) 4s (B) 4p (C) 3d (D) 5f. Consider following statements. A. Splitting of spectral line occurs wen placed in a magnetic field or in an electric field B. In case of s-orbital, te density of te carge cloud is te greatest at te nucleus and falls off wit te distance. Te density ( at a particular distance) is uniform C. Electron-density is concentrated along a particular direction in case of p-orbital. D. A p-orbital can take maximum of six electrons. Select te correct option (A) A, B, D (B) A, B, C (C) B, C, D (D) A, C, D Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 3

15 Matc te column 3. Column I Column II (i) Aufbau principle (ii) de broglie (iii) Angular momentum (iv) Hund s rule (v) Balmer series (vi) Planck s law (a) Line spectrum in visible region (b) Maximum multiplicity of electron (c) Poton (d) = /(mv) (e) Electronic configuration (f) mvr 4. Column I Column II (i) Catode rays (ii) Dumb-bell (iii) Alpa particles (iv) Moseley (v) Heisenberg (vi) X-rays (a) Helium nuclei (b) Uncertainty principle (c) Electromagnetic radiation (d) p-orbital (e) Atomic number (f) Electrons 5. Frequency = f, Time period = T, Energy of n t orbit = E n, radius of n t orbit = r n, Atomic number = Z, Orbit number = n Column I Column II (i) f (a) n 3 (ii) T (b) Z (iii) E n (c) n (iv) r n (d) Z 6. Column I Column II (i) Lyman series (a) maximum number of spectral line observed = 6 (ii) Balmer series (b) maximum number of spectral line observed = (iii) In a sample of H-atom for 5 transition 8R (c) nd line as wave number 9 3R (iv) In a single isolated H-atom for 3 transition (d) nd line as wave number 6 (e) Total number of spectral line is 0. Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 4

16 PART - I : MIXED OBJECTIVE * Marked Questions are aving more tan one correct option. Single Coice type. Multiple of fine structure of spectral lines is due to - (A) Presence of main energy levels (B) Presence of sub- levels (C) Presence of electronic configuration (D) Is not a caracteristics of te atom.. Te quantum number not obtained from te Scrodinger s wave equation is - (A) n (B) l (C) m (D) s 3. Wave mecanical model of te atom depends upon - (A) de-broglie concept of dual nature of electron (B) Heisenberg uncertainty principle (C) Scrodinger uncertainty principle (D) All 4. Wic orbital is dumb-bell saped - (A) s-orbital (B) p-orbital (C) d-orbital (D) f-orbital 5. Wic of te following subsell can accommodate as many as 0 electrons - (A) d (B) 3d (C) 3dxy (D) 3dz 6. "No two electrons in an atom can ave te same set of four quantum numbers. "Tis principle was enunciated by - (A) Heisenberg (B) Pauli (C) Maxwell (D) de Broglie. 7. How many sperical nodes are present in a 4s orbital in ydrogen atom - (A) 0 (B) (C) (D) 3 8. Minimum core carge is sown by te atom - (A) O (B) Na (C) N (D) Mg 9. Wic one of te statement of quantum numbers is false - (A) Quantum number were proposed out of necessity in Bor model of te atom. (B) Knowing n and l it possible to designated a subsell. (C) Te principal quantum number alone can give te complete energy of an electron in any atom. (D) Azimutal quantum number refers to te subsell to wic an electron belongs and describes te motion of te electron. 0. I.P. of ydrogen atom is equal to 3.6 ev. Wat is te energy required for te process : He + + energy He + + e (A) 3.6 ev (B) 3.6 ev (C) ev (D) None of tese. If elements wit principal quantum number n > 4 is not allowed in nature, te number of possible elements would be - (A) 60 (B) 3 (C) 64 (D) 50. Te correct statement(s) about Bor s orbits of ydrogen atom is/are - (A) r = n 4 me (C) Angular momentum (L) = n (B) K.E. of te electron = / (P. E. of te electron) (D) All te above Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 5

17 3. In centre-symmetrical system, te orbital angular momentum, a measure of te momentum of a particle travelling around te nucleus, is quantised. Its magnitude is - (A) ( ) (B) ( ) (C) s( s ) (D) s( s ) 4. If te values of (n + ) is not > 3, ten te maximum number of electron in all te orbital would be - (A) (B) 0 (C) (D) 6 5. It is not possible to explain te pauli's exclusion principle wit te elp of tis atom - (A) B (B) Be (C) C (D) H 6. Eac orbital as a nodal plane. Wic of te following statements about nodal planes are not true - (A) A plane on wic tere is zero probability tat te electron will be found (B) A plane on wic tere is maximum probability tat te electron will be found (C) Bot (D) None 7. One energy difference between te states n = and n = 3 is E ev, in ydrogen atom. Te ionisation potential of H atom is - (A) 3. E (B) 5. 6E (C) 7. E (D) 3. E 8. Magnetic moments of V(Z = 3), Cr(Z = 4), Mn(Z = 5) are x, y, z. Hence - (A) x = y = z (B) x < y < z (C) x < z < y (D) z < y < x 9. An electron, a proton and an alpa particle ave kinetic energies of 6E, 4E and E respectively. Wat is te qualitative order of teir de Broglie wavelengts - (A) e > p = (B) p = a > e (C) p < e > a (D) a < e» p 0. Consider te following ions -. Ni +. Co + 3. Cr + 4. Fe 3+ (Atomic numbers : Cr = 4, Fe = 6, Co = 7, Ni = 8) Te correct sequence of te increasing order of te number of unpaired electrons in tese ions is - (A),, 3, 4 (B) 4,, 3, (C), 3,, 4 (D) 3, 4,,. Wat are te values of te orbital angular momentum of an electron in te orbitals s, 3s, 3d and p- (A) 0, 0, 6, (B),, 4, (C) 0,, 6, 3 (D) 0, 0, 0, 6. In an atom two electron move around te nucleus in circular orbits of radii R and 4R. Te ratio of te time taken by tem to complete one revolution - (A) : 4 (B) 4 : (C) : 8 (D) 8 : 7 3. A beam of electrons is accelerated by a potential difference of 0000 volts. Te wavelengt of te wave associated wit it will be - (A) 0.03 Å (B).3 Å (C) 0.3 Å (D) None of tese 4. If te number of electrons in p-orbital are two, ten wic one of te following is in accordance wit Hund s rule - (A) p 0 0 x py p z (B) p 0 0 x py p z (C) p 0 0 x py p z (D) p x p y p 0 z 5. If tere are six energy levels in H atom ten te number of lines its emission spectrum in ultra voilet region will be - (A) 6 (B) 5 (C) 4 (D) 3 6. Magnetic moment of X 3+ ion of 3d series is 35 BM. Wat is atomic number of X 3+? (A) 5 (B) 6 (C) 7 (D) 8 Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 6

18 7. An electron is moving wit te velocity equal to 0% of te velocity of ligt. Its de-broglie wave lengt will be- (A) cm (B) cm (C) Cm (D) None of tese 8. Correct set of four quantum numbers for te valence (outer most) electron of rubidium (Z = 37) is - (A) 5,0,0, + (B) 5,,0, + (C) 5,,, + (D) 5,0,0, 3 9. Ratio of time period of electron in first and second orbit of H-atom would be - (A) : 8 (B) : 8 (C) : (D) : 30. If x is te velocity of an electron in first Bor s orbit. Wat would be te velocity of te electron in tird Bor s orbit - (A) x 9 (B) x 3 (C) 3x (D) 9 x 3. Te total energy associated per quanta wit ligt of wavelengt 600 nm - (A) erg (B) erg (C) erg (D) erg 3. Te number of revolution/sec. made by electron in 3rd orbit of ydrogen atom - (A) (B) (C) (D) Angular and sperical nodes in 3s - (A), (B), 0 (C), 0 (D) 0, 34. Te magnetic moment of V 4+ ion - (A).73 (B).4 (C) 3.46 (D) 35. Wic orbital represents te following set of quantum numbers n = 3, = 0, m = 0, s = +/ - (A) 3p (B) s (C) 3s (D) p 36. Te number of unpaired electrons in Zn + - (A) 0 (B) (C) (D) Te uncertainly in velocity of electron aving uncertainty in its position of Å - (A) m/s (B) m/s (C) m/s (D) m/s 38. If ionisation energy of ydrogen atom is 3.6 ev. I.E. of Li + will be - (A) 3.6 ev (B) 0.4 ev (C) 40.8 ev (D).4 ev 39. Te wavelengt of tird lyman series of ydrogen atom is approximately - (A) 0 7 m (B) 0 8 m (C) 0 6 m (D) 0 5 m 40. Te number of waves made by a Bor electron in one complete revolution in its 3rd orbit - (A) (B) (C) 3 (D) 4 4. If potential energy of an electron in ydrogen atom is x ev, ten its kinetic energy will be - (A) x ev (B) x ev (C) x ev (D) x/ ev 4. Te number of orbitals in n = 3 are - (A) (B) 3 (C) 5 (D) Maximum value (n + l + m) for unpaired electrons in second excited state of clorine 7 Cl is: (A) 8 (B) 5 (C) 0 (D) none of tese 44. If tere are tree possible values ( /, 0, +/) for te spin quantum, ten electronic configuration of K(9) will be: (A) s 3, s 3 p 9, 3s 3 3p (B) s, s p 6, 3s 3p 6, 4s (C) s, s p 9, 3s 3p 4 (D) none of tese Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 7

19 45. Te fourt electron of Beryllium as te following four quantum numbers in te order n, l, m & s (A),0,, (B),,, (C), 0,0, (D),,0, 46. A proton and an -particle are accelerated troug te same potential difference from rest. Ten te ratio of teir de Broglie wavelengt is : (A) (B) (C) (D) / More tan one coice type 47. Te spectrum of He + is expected to be similar to tat of : (A) Li + (B) He (C) H (D) Na 48. Select te correct relations on te basis of Bor s teory: (A) velocity of electron n (B) frequency of revolution 3 n (C) radius of orbit n z (D) force on electron 4 n 49. Te ratio of (E E ) to (E 4 E 3 ) for te ydrogen atom is not approximately equal to: (A) 0 (B) 5 (C) 7 (D) 50. Wic of te following statement is not correct - (A) Number of angular nodes = n (B) Number of radial nodes = (C) Total number of nodes = n (D) All 5. If Hund s rule is followed, magnetic moment of Fe +, Mn + and Cr all aving 4 electrons will not be in order - (A) Fe + < Mn + < Cr (B) Fe + < Cr = Mn + (C) Fe + = Mn + < Cr (D) Mn + = Cr < Fe + 5. Wic of te following are not correct about te e/m ratio for catode rays - (A) Is constant (B) Varies as te atomic number of te element forming catode in te discarge tube canges (C) Varies as atomic number of te gas in te discarge tube varies (D) Has te smallest value wen te discarge tube is filled wit ydrogen 53. Wic are te incorrect relationsip : (A) E of H = / E of He + = /3 E 3 of Li + = /4 E 4 of Be 3+ (B) E (H) = E (He + ) = E 3 (Li + ) = E 4 (Be 3+ ) (C) E (H) = E (He + ) = 3E 3 (Li + ) = 4E 4 (Be 3+ ) (D) No relation 54. Wic of te followings are not correct about te maximum probability of finding electron in te d xy orbital? (A) Along te x axis (B) Along te y axis (C) At an angle of 45º from te x and y axis (D) At an angle of 90º from te x and y axis Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 8

20 PART - II : SUBJECTIVE QUESTIONS. Wat is te number of potons of ligt wit a wavelengt of 4000 pm tat provide J of energy?. A poton of wavelengt m strikes on metal surface, te work function of te metal being.3 ev. Calculate (i) te energy of te poton (ev), (ii) te kinetic energy of te emission, and (iii) te velocity of te potoelectron ( ev = J). 3. Ionization energy of a ydrogen-like ion A is greater tan tat of anoter ydrogen like ion B. Let r, u, E and L represent te radius of te orbit, speed of te electron, total energy of te electron and angular momentum of te electron respectively (for te same n). In ground state 4. Tere are two samples of H and He atom. Bot are in some excited state. In ydrogen atom total number of lines observed in Balmer series is 4 and in He + atom total number of lines observed in pascen series is. Electron in ydrogen sample make transitions to lower states from its excited state, ten te poton corresponding to te line of maximum energy line of Balmer series of H sample is used to furter excite te already excited He + sample. Ten maximum excitation level of He + sample will be : 5. Poton aving energy equivalent to te binding energy of 4t state of He + ion is used to eject an electron from te metal wit K.E. ev. If electron is furter accelerated troug te potential difference of 4V ten te minimum value of de Broglie wavelengt associated wit te electron is : ( = 6.6 x 0 34 J-s, m e = 9. x 0 3 kg, ev =.6 x 0 9 J) 6. In Balmer series of lines of ydrogen spectrum, te first line from te red end corresponds to wic one of te following inter-orbit jumps of te electron for Bor orbits in an atom of ydrogen? 7. Wic transition in Li + would ave te same wavelengt as te 4 transition in He + ion? 8. Potons of equal energy were incident on two different gas samples. One sample containing H-atoms in te ground state and te oter sample containing H-atoms in some excited state wit a principal quantum number n. Te potonic beams totally ionise te H-atoms. If te difference in te kinetic energy of te ejected electrons in te two different cases is.75 ev. Ten find te principal quantum number n of te excited state. 9. Te speed of a proton is one undredt of te speed of ligt in vacuum. Wat is its de-broglie wavelengt? Assume tat one mole of protons as a mass equal to one gram [ = 6.66 x 0 7 erg sec] - 0. Iodine molecule dissociates into atom after absorbing ligt of 4500 Å. Te K.E. of iodine atoms if B.E. of I is 40 kj mol -. Wat is te maximum number of emission lines wen te excited electron of a H atom in n = 6 drops to te ground state?. Explain, giving reasons, wic of te following sets of quantum numbers are not possible. (a) n = 0, l = 0, m l = 0, m s = + (b) n =, l = 0, m l = 0, m s = (c) n =, l =, m l = 0, m s = + (d) n =, l =, m l = 0, m s = (e) n = 3, l = 3, m l = 3, m s = + (f) n = 3, l =, m l = 0, m s = + Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 9

21 PART-I IIT-JEE (PREVIOUS YEARS PROBLEMS). Te wavelengt associated wit a golf ball weiging 00g and moving at a speed of 5 m/ is of te order [IIT-00] (A) 0 0 m (B) 0 0 m (C) 0 30 m (D) 0 40 m. Te quantum numbers +/ and / for te electron spin represent [IIT-00] (A) rotation of te electron in clockwise and anticlockwise direction respectively (B) rotation of te electron in anticlockwise and clockwise direction respectively (C) magnetic moment of te electron pointing up and down respectively (D) two quantum mecanical spin states wic ave no classical analogue 3. Ruterford s experiment, wic estabilised te nuclear model of te atom, used a beam of - [IIT-00] (A) particles, wic impinged on a metal foil and got absorbed (B) rays, wic impinged on a metal foil and ejected electrons (C) elium atoms, wic impinged on a metal foil and got scattered (D) elium nuclei, wic impinged on a metal foil and got scattered 4. If te nitrogen atom ad electronic configuration s, it would ave energy lower tan tat of te normal ground state configuration s s p 3, because te electrons would be closer to te nucleus. Yet, s 7 is not observed because it violates. [IIT-00] (A) Heisenberg uncertainty principle (B) Hund s rule (C) Pauli s exclusion principle (D) Bor postulates of stationary orbits. 5. Calculate te energy required to excite one litre Hydrogen gas at atm and 98 K to first excited state of atomic ydrogen. Te energy for te dissociation of H-H bond is 436 kj mol Te orbit aving Bor radius equal to st Bor orbit of H atom is [JEE 004, 3/44] (A) n = of He + (B) n = of B +4 (C) n = 3 of Li + (D) n = of Be Find wavelengt for 00 g particle moving wit velocity 00 m/s. [JEE 004,.5/44] 8. (A) Using Bor s model for ydrogen atom, find te speed of electron in te first orbit if te Bor s radius is a 0 = m. Find debroglie wavelengt of te electron also. (B) Find te orbital angular momentum of electron if it is in p orbital of H in terms of.[jee 005,4/44] 9. According to Bor s teory, E n = Total energy K n = Kinetic energy V n = Potential energy r n = Radius of n t orbit [JEE 006,6/84] Matc te following: Column I (A) V n / K n =? (p) 0 Column II (B) If radius of n t orbit E n x, x =? (q) (C) Angular momentum in lowest orbital (r) y (D) Z, y? (s) r n Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 0

22 Paragrap for Question Nos. 0 to Te ydrogen-like species Li + is in a sperically symmetric state S wit one radial node. Upon absorbing ligt te ion undergoes transition to a state S. Te state S as one radial node and its energy is equal to te ground state energy of te ydrogen atom. 0. Te state S is : [JEE 00, 3/63] (A) s (B) s (C) p (D) 3s. Energy of te state S in units of te ydrogen atom ground state energy is : [JEE 00, 3/63] (A) 0.75 (B).50 (C).5 (D) Te orbital angular momentum quantum number of te state S is : [JEE 00, 3/63] (A) 0 (B) (C) (D) 3 3. Te maximum number of electrons tat can ave principal quantum number, n = 3 and spin quantum number, m s = ½, is [IIT-JEE - 0] 4. Te work function () of some metals is listed below. Te number of metals wic will sow potoelectric effect wen ligt of 300 nm wavelengt falls on te metals is [IIT-JEE - 0] Metal (ev) Li Na K Mg Cu Ag Fe Pt W Te kinetic energy of an electron in te second Bor orbit of a ydrogen atom is [a 0 is Bor radius] [IIT-JEE- 0] (A) 4 ma 0 (B) 6 ma 0 (C) 3 ma 0 (D) 64 ma 0 PART - II : AIEEE (PREVIOUS YEARS PROBLEMS). Wic of te following ions as te maximum magnetic moment? [AIEEE - 00] () Mn + () Fe + (3) Ti + (4) Cr +.. Energy of H-atom in te ground state is 3.6 ev, ence energy in te second excited state is : [AIEEE 0] () 6.8 ev () 3.4 ev (3).5 ev (4) 4.53 ev 3. Uncertainity in position of a particle of 5 g in space is 0 5 m. Hence, Uncertainity in velocity (m.sec ) is : (plank s constant, = Js) [AIEEE 0] (). 0 8 () (3) (4) Te de-broglie wavelengt of a tennis ball of mass 60 g moving wit a velocity of 0 m/s is approximately (planck s constant, = J-s) [AIEEE 03] () 0 33 m () 0 3 m (3) 0 6 m (4) 0 5 m 5. In Bor series of lines of ydrogen spectrum, te tird line from te red end corresponds to wic one of te following inner-orbit jumps of te electron for Bor orbits in an atom of ydrogen? [AIEEE 03] () 3 () 5 (3) 4 (4) 5 Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE #

23 6. Te numbers of d-electrons retained in Fe + (atomic number Fe = 6) ion is [AIEEE 03] () 3 () 4 (3) 5 (4) 6 7. Te orbital angular momentum for an electron revolving in an orbit is given by ( l ). Tis momentum for an s-electron will be given by : [AIEEE 03] () +. () Zero (3) (4). 8. Te wavelengt of te radiation emitted, wen in a ydrogen atom electron falls from infinity to stationary state, would be (Rydberg constant = m ) [AIEEE 04] () 9 nm () 9 nm (3) 406 (4) nm 9. Wic of te following set a of quantum numbers is correct for an electron in 4f orbital? [AIEEE 04] () n = 4, l =3, m = +4, s = +/ () n = 4, l = 4, m = 4, s = / (3) n = 4, l = 3, m = +, s = +/ (4) n = 3, l=, m =, s = +/ 0. Consider te ground state of Cr atom (Z = 4). Te numbers of electrons wit te azimutal quantum numbers, = and are, respectively [AIEEE 04] () and 4 () and 5 (3) 6 and 4 (4) 6 and 5. Wic of te following statements in relation to te ydrogen atom is correct? [AIEEE 05] () 3s, 3p and 3d orbitals all ave te same energy () 3s and 3p orbitals are of lower energy tan 3d orbital (3) 3p orbital is lower in energy tan 3d orbital (4) 3s orbital is lower in energy tan 3p orbital. In a multi-electron atom, wic of te following orbitals described by te tree quantum numbers will ave te same energy in te absence of magnetic and electric field? [AIEEE 05] (i) n =, l = 0, m = 0 (ii) n =, l = 0, m = 0 (iii) n =, l =, m = (iv) n = 3, l =, m = (v) n = 3, l =, m = 0 () (iv) and (v) () (iii) and (iv) (3) (ii) and (iii) (4) (i) and (ii) 3. Uncertainity in te position of an electron (mass = Kg) moving wit a velocity 300 m.sec, Accurate upto 0.00%, will be : ( = J-s) [AIEEE 06] () 9. 0 m () m (3).9 0 m (4) m 4. According to Bor s teory, te angular momentum of an electron in 5 t orbit is : [AIEEE 06] () 5 ().0 (3) 0 (4).5 5. Te spin-only magnetic moment [in units of Bor magneton ( )] of Ni + in aqueous solution would be (Atomic number : Ni = 8) [AIEEE 06] ().84 () 4.90 (3) 0 (4) Wic of te following nuclear reactions will generate an isotope? [AIEEE 07, 3/0] () Neutron particle emission () Positron emission (3) -particle emission (4) -particle emission Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE #

24 7. Te ionisation entalpy of ydrogen atom is J mol. Te energy required to excite te electron in te atom from n = to n = is [AIEEE 08, 3/05] () J mol () J mol (3) J mol (4) J mol 8. Wic of te following set of quantum numbers represents te igest energy of an atom? [AIEEE 08,3/05] () n = 3, l = 0, m = 0, s = + () n = 3, l =, m =, s = + (3) n = 3, l =, m =, s = + (4) n = 4, l = 0, m = 0, s = + 9. Calculate te wavelengt (in nanometer) associated wit a proton moving at m s (Mass of proton = kg and = J-s) : [AIEEE 009, 4/44] () 0.40 nm ().5 nm (4) 4.0 nm (4) 0.03 nm 0. In an atom, an electron is moving wit a speed of 600 m/s wit an accuracy of 0.005%. Certainity wit wic te position of te electron can be located is ( = kg m s, mass of electron, e m = kg): [AIEEE 009, 4/44] () m () m (3) m (4) m. Te energy required to break one mole of Cl Cl bonds in Cl is 4 kj mol. Te longest wavelengt of ligt capable of breaking a single Cl Cl bond is (c = m s and N A = mol ) [AIEEE 00, 4/44] () 594 nm () 640 nm (3) 700 nm (4) 494 nm. Ionisation energy of He + is [AIEEE 00, 4/44] J atom. Te energy of te first stationary state (n = ) of Li + is : () 0.40 nm ().5 nm (3) 4.0 nm (4) 0.03 nm 3. Te electrons identified by quantum numbers n and l : [AIEEE-0] (A) n = 4, l = (B) n = 4, l = 0 (C) n = 3, l = (D) n = 3, l = can be placed in order of increasing energy as : () (C) < (D) < (B) < (A) () (D) < (B) < (C) < (A) (3) (B) < (D) < (A) < (C) (4) (A) < (C) < (B) < (D) Z 4. Energy of an electron is given by E = J n. Wavelengt of ligt required to excit an electron in an ydrogen atom from level n = to n = will be : ( = Js and c = ms ) [JEE Mains - 03] () m () m (3) m (4) m Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 3

25 BOARD PATTERN QUESTIONS. (i) Calculate te number of electrons wic will togeter weig one gram. (ii) Calculate te mass and carge of one mole of electrons.. (i) Calculate te total number of electrons present in one mole of metane. (ii) Find (a) te total number and (b) te total mass of neutrons in 7 mg of 4 C. (Assume tat mass of a neutron = kg). (iii) Find (a) te total number and (b) te total mass of protons in 34 mg of NH 3 at STP. Will te answer cange if te temperature and pressure are canged? 3. How many neutrons and protons are tere in te following nuclei? O, Mg, Fe, 3 6 C, Sr 4. Write te complete symbol for te atom wit te given atomic number (Z) and atomic mass (A) (i) Z = 7, A = 35. (ii) Z = 9, A = 33. (iii) Z = 4, A = Yellow ligt emitted from a sodium lamp as a wavelengt () of 580 nm. Calculate te frequency () and wavenumber ( ) of te yellow ligt. 6. Find energy of eac of te potons wic (i) correspond to ligt of frequency 30 5 Hz. (ii) ave wavelengt of 0.50 Å. 7. Calculate te wavelengt, frequency and wavenumber of a ligt wave wose period is s. 8. Electromagnetic radiation of wavelengt 4 nm is just sufficient to ionise te sodium atom. Calculate te ionisation energy of sodium in kj mol. 9. A 5 watt bulb emits monocromatic yellow ligt of wavelengt of 0.57m. Calculate te rate of emission of quanta per second. 0. Electrons are emitted wit zero velocity from a metal surface wen it is exposed to radiation of wavelengt 6800 Å. Calculate tresold frequency ( 0 ) and work function (W 0 ) of te metal.. Wat is te wavelengt of ligt emitted wen te electron in a ydrogen atom undergoes transition from an energy level wit n = 4 to an energy level wit n =?. How muc energy is required to ionise a H atom if te electron occupies n = 5 orbit? Compare your answer wit te ionization entalpy of H atom ( energy required to remove te electron from n = orbit). 3. (i) Te energy associated wit te first orbit in te ydrogen atom is J atom. Wat is te energy associated wit te fift orbit? (ii) Calculate te radius of Bor s fift orbit for ydrogen atom. 4. Calculate te wavenumber for te longest wavelengt transition in te Balmer series of atomic ydrogen. 5. Wat is te energy in joules, required to sift te electron of te ydrogen atom from te first Bor orbit to te fift Bor orbit and wat is te wavelengt of te ligt emitted wen te electron returns to te ground state? Te ground state electron energy is.8 0 ergs. Pysical & Inorganic By B.Tec. IIT Deli A-479 Indra viar, kota P () () Organic Cemistry By ATOMIC STRUCTURE # 4