Chem periodicity

Question 1

Bonding and structure for Na2O, MgO, Al2O3

Answer 1

Na2O, MgO: giant ionic lattice
Al2O3: giant ionic lattice with covalent character
Strong electrostatic forces of attraction between oppositely charged ions

Question 2

Bonding and structure for SiO2

Answer 2

Giant covalent structure, strong covalent bonds between Si and O atoms

Question 3

Bonding and structure for P4O10 and SO3

Answer 3

Simple molecular
Intermolecular weak id-id interactions between molecules, strength

Question 4

Why MgO has a higher mp than Na2O

Answer 4

stronger electrostatic attraction between highly charged Mg2+ and O2-
relate to LE equation

Question 5

why Al2O3 has a lower mp than MgO

Answer 5

Al2O3 has some degree of covalent character due to the high charge density and high polarising power of Al3+ ion

Question 6

Reaction of oxides with water

Answer 6

Na2O: reacts vigorously with water
MgO: slightly soluble in water to give a weak alkaline solution, due to strong ionic bonds in MgO
Al2O3 and SiO2: does not dissolve in water due to high LE, strong covalent bonds between SI and O atoms
P4O10 and SO3: forms H2PO4 and H2SO4 acid

Question 7

Decreasing pH of products formed from oxide and water

Answer 7

bonding varies from ionic to covalent, oxides vary from basic to amphoteric to acidic
decreasing difference in electronegativity

Question 8

Acid base reaction of oxides and hydroxides

Answer 8

Na2O, MgO: forms NaCl/MgCl
Al2O3: forms Na+[Al(OH)4]- complex
SiO2, P4O10, SO3: forms Na2SiO3, Na3PO4, Na2SO4

Question 9

reactions of chlorides with water

Answer 9

NaCl: hydration
MgCl2: hydration, slight hydrolysis
AlCl3: hydration to form [Al(H2O)6]3+
hydrolysis to form [Al(H2O)5(OH)]2+
SiCl4: hydrolysis to from SiO2 and H2O
PCl5: hydrolysis to form H3PO4 and HCl