PH 3 + H + à PH 4 PH 4. H 3 O + is pyramidal, bond angle 107 ; steric 4, 1LP Lone pair from O donated to H +

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$Metallic bonding AS Bonding & Periodicity Test: Answers Ionic Bonding Ti is a giant metallic lacce. There is strong electrosta2c afrac2on between posi2ve metal ions and sea of delocalised electrons.$ Na conducts and NaCl does not conduct. Delocalised electrons flow through the metal and transfer charge. Ions are rela2vely fixed in solid NaCl, so it does not conduct.

Na conducts and NaCl does not conduct. Delocalised electrons flow through the metal and transfer charge. Ions are rela2vely fixed in solid NaCl, so it does not conduct.

$There is strong afrac2on between oppositely charged Mg 2 and O 2- ions. Iodide ion has larger atomic radius.$ lacce. Covalent and da2ve covalent bonding PH 3 is pyramidal steric 4, 1 LP bond angle 107 PH 3 H à PH 4 PH 4 formed by lone pair from P atom being donated to H.

lacce. Covalent and da2ve covalent bonding PH 3 is pyramidal steric 4, 1 LP bond angle 107 PH 3 H à PH 4 PH 4 formed by lone pair from P atom being donated to H.

1 Metallic bonding AS Bonding & Periodicity Test: Answers Ionic Bonding Ti is a giant metallic lacce. There is strong electrosta2c afrac2on between posi2ve metal ions and sea of delocalised electrons. Layers of atoms slide over one another when hammered, but, in the new metallic shape, the same strong metallic bonding (and bond strength) is re- formed between metal ions and delocalised electrons. Na conducts and NaCl does not conduct. Delocalised electrons flow through the metal and transfer charge. Ions are rela2vely fixed in solid NaCl, so it does not conduct. However, aqueous and molten NaCl can conduct as Na Cl - are mobile and able to transfer electrical charge. MgO is a giant ionic lacce. There is strong afrac2on between oppositely charged Mg 2 and O 2- ions. Iodide ion has larger atomic radius. Thus, there is increased separa2on between Na and I - nuclei, which decreases the strength of the ionic afrac2ve force between ions, thus decreasing the overall strength of the ionically bonded giant lacce. Covalent and da2ve covalent bonding PH 3 is pyramidal steric 4, 1 LP bond angle 107 PH 3 H à PH 4 PH 4 formed by lone pair from P atom being donated to H. This is a coordinate (da2ve covalent) bond. Steric 4, No LP, bond angle H 3 O is pyramidal, bond angle 107 ; steric 4, 1LP Lone pair from O donated to H F How bond shapes are formed: Equal repulsion between bonding electron pair ligands Lone pair from F donated to B atom to form da2ve covalent bond BF 3 trigonal planar steric 3, No LP, bond angle 120 BF 4 tetrahedral steric 4, No LP, bond angle Cl M r 267 = Al 2 Cl 6 Lone pair from Cl donated to Al atom to form da2ve covalent bond in AlCl 4 1

2 Bond Polarity Electronega2vity is the ability of an atom to afract electron density from a pair of electrons contained in a covalent bond CH 4 intermolecular force= van der Waals ; NH 3 intermolecular force= hydrogen bonding Large electronega2vity difference between N and H ( =0.9) This forms a dipole charge separa2on Nδ and Hδ within the N- H covalent bond Lone pair of electrons on N atom is afracted to (hydrogen bonds with) Hδ of adjacent NH 3 molecule NO has covalent bonding as there is only a small electronega2vity difference between N and O (difference is 0.5 units according to table of electronega2vity values) Forces between molecules The hydrogen bonding intermolecular forces that exist between methanol molecules are much stronger than the van der Waals forces that exist between oxygen molecules, hence methanol has a higher b.p. oxygen. Intermolecular forces: F 2 is van der Waals, CH 3 F is dipole- dipole, HF is hydrogen bonding. Large electronega2vity difference between F and H This forms a dipole charge separa2on Fδ and Hδ within the H- F covalent bond Lone pair of electrons on F atom is afracted to (hydrogen bonds with) Hδ of adjacent HF molecule The molecular mass (size) of hydrogen halides increases as the group is descended, hence there is increasing strength of van der Waals forces of afrac2on. Conversely, the difference in electronega2vity between hydrogen and halogen decreases as the group is descended, hence there is decreased dipole- dipole intermolecular forces of afrac2on. Overall, these trends culminate in an increased boiling point as the hydrogen halide group is descended. Hydrogen bonding exists between NH 3 and H 2 O or Hydrogen bonding exists between HF molecules The hydrogen bonding intermolecular forces (IMF) that exist between HF molecules are much stronger than the van der Waals forces that exist between F 2 molecules. Hence, lower energy is required to break IMF of liquid F 2 so F 2 has lower boiling point. 2

Bonding and physical proper2es and states of mafer Iodine is molecular crystal and graphite is giant covalent macromolecule Graphite: composed of layers of hexagonal covalently bound carbon atoms

$The increased molecular size of the compounds formed between hydrogen and group VI elements as the Group is descended means there are increased van der Waals afrac2ve forces between molecules, hence$

3 Bonding and physical proper2es and states of mafer Iodine is molecular crystal and graphite is giant covalent macromolecule Graphite: composed of layers of hexagonal covalently bound carbon atoms that are separated by weak van der Waals forces between the layers. Strong covalent bonds needs to be broken to melt graphite, hence it has a high mel2ng point. The hydrogen bonding intermolecular forces (IMF) that exist between H 2 O molecules are much stronger than the van der Waals and dipole- dipole forces that exist between H 2 S molecules. The increased molecular size of the compounds formed between hydrogen and group VI elements as the Group is descended means there are increased van der Waals afrac2ve forces between molecules, hence a trend towards increased boiling point. Shapes of simple molecules BeCl 2 Steric 2, no LP Linear, 180 bond angle Cl 2 O.. NHF 2 Steric 4, one LP pyramidal, 107 bond angle N - NH 2 BF 3 Steric 3, no LP Trigonal planar, 120 bond angles AsCl 4 ion has a bond angle of 109.5, because the shape formed has equal repulsion between 4 bonding (electron pair) ligands. As AsF 5 Steric 5, no LP Trigonal Bipyramidal, 90 and 120 bond angles ClF 2 3

4 Period 3: decreasing atomic radius, increasing 1 st IE & trends in m.p. Q6 Decreasing atomic radius: increasing nuclear charge, similar electron shielding increased effec2ve nuclear charge density greater afrac2on of valence electron(s) by nucleus decreased atomic radius 1 st IE: the energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous mono- posi2ve ions. X(g) à X (g) e - Mg (g) à Mg 2 (g) e - More energy is required to remove an electron from a posi2vely charged ion than a neutral ion. Also, Mg has a smaller atomic radius than Mg, so greater energy is needed to overcome the increased nuclear afrac2ve force that is holding the outer shell electron closer to the nucleus. Increasing 1 st IE: increasing nuclear charge, similar electron shielding increased effec2ve nuclear charge density greater afrac2on of valence electron(s) by nucleus and decreased atomic radius more energy needed to remove outershell (valence) electron Sulfur: less than expected increase in 1 st IE: Electron pair repulsion in the 3p suborbital means less energy is required to remove the valence e - Q7 Q8 Aluminium: less than expected increase in 1 st IE: The valence electron is located in a higher energy 3p orbital, which is further away from the nucleus and its nuclear afrac2ve force, hence less energy is required to remove the valence e - X is Aluminium (considerable increase in 1 st IE between 3 rd and 4 th electron removal) Q9 S 8 and P 4 exist as simple molecular structures with weak van der Waals intermolecular forces between molecules. However, as S 8 is a larger sized molecule than P 4, it has stronger vdw. Thus, more energy is needed to break the IMF of S 8 so it has a higher mel2ng point. 0 1 Silicon is a giant covalent macromolecule. Each silicon atom is covalently bonded to 4 other silicon atoms in a diamond cubic crystal structure. Considerable energy is needed to break the strong covalent bonds within this giant structure arrangement, hence silicon has a high m.p. Al and Na exist as giant lacces of metallic bonded atoms. However, Al, compared to Na, has a: higher metal ion charge (3 vs. 1) more delocalised electrons per metal ion smaller atomic radius than Na (closer distance between metal ion and delocalised e - sea). In combina2on, these factors ensure Al achieves stronger electrosta2c afrac2on between the more posi2vely charged metal ions and higher e - density delocalised e - sea, compared to Na. Hence, metallic bonding is stronger in Al and more energy is needed to overcome this afrac2ve force and melt Al compared to Na. 4

Extended wri2ng ques2on: Bonding NaCl is an ionic compound. Oppositely charged ions are held together by electrosta2c forces in a giant ionic cubic lacce.

In each water molecule, a single oxygen atom is covalently bonded to two hydrogen atoms forming an angular shaped molecule.

Overall, ionic bonding within the lacce of NaCl is stronger than the intermolecular forces holding water molecules together in ice.

5 Extended wri2ng ques2on: Bonding NaCl is an ionic compound. Oppositely charged ions are held together by electrosta2c forces in a giant ionic cubic lacce. Water is composed of covalent molecules that are held together by intermolecular hydrogen bonds. In each water molecule, a single oxygen atom is covalently bonded to two hydrogen atoms forming an angular shaped molecule. As ice, water molecules form a hexagonal crystal lacce where two hydrogen bonds form per molecule of water. Overall, ionic bonding within the lacce of NaCl is stronger than the intermolecular forces holding water molecules together in ice. Hence, as more energy is needed to separate the separate the Na Cl - ions compared to breaking down hydrogen bonds in ice, NaCl has a higher m.p. than ice. SF 4 is steric 5, 4 bonding ligands and one lone pair Structure is based on equal repulsion between bonding ligands and lone pair Hence, molecule structure is see- saw shape. The electron pair distribu2on is trigonal bipyramidal with the lone pair located on the axial or equatorial loca2on. There is slight lone pair- bond pair repulsion that pushes the S- F bonds closer together, hence bond angles are slightly <120 and <180, respec2vely. Extended wri2ng: Periodicity Elements in the p block have their outer electron(s) in p orbitals or levels or sub- shells e.g. Carbon 1s 2 2s 2 2p 2 Periodicity: pafern in the change in the proper2es of a row of elements that is repeated in the next row (underneath or above the index row). Atomic radius decreases and electronega2vity increases, across Period 3. Both trends share common reasons: increasing nuclear charge, similar electron shielding increased effec2ve nuclear charge density greater afrac2on of valence electron(s) by nucleus and decreased atomic radius. Conduc2vity: Metals Na, Mg, Al conduct electricity due to free delocalised electrons being able to transfer electrical charge through the metallic bonded structure. The electrical conduc2vity increases from Na to Al due to increased e - density with the sea of delocalised e -. Non- metals (P, S, Cl) exist as covalent molecules and are unable to conduct electricity due to an absence of mobile delocalised high energy level electrons. Electrical conduc2vity of silicon: silicon is a metalloid giant covalent macromolecule. At room temperature, few valence electrons are mobile (so poor conduc2vity), however, at higher temperature, 5 more electrons are promoted to higher energy levels and electrical conduc2vity increases.

DEFINITION. The electrostatic force of attraction between oppositely charged ions

DEFINITION. The electrostatic force of attraction between oppositely charged ions DEFINITION The electrostatic force of attraction between oppositely charged ions Usually occurs when a metal bonds with a non-metal Ions are formed by complete electron transfer from the metal atoms to