Periodicity

Question 1

Reaction of Sodium Oxide & Magnesium Oxide with Water (product, solution, pH)

Answer 1

Na2O -> forms NaOH, strongly alkaline solution with pH 13

MgO -> forms Mg(OH)2, weakly alkaline solution, pH 9

Question 2

Reaction of Phosphorus Oxide & Sulfur Oxide with water (Product, Solution, pH)

Answer 2

P4O10 -> Forms 4x H3PO4, weakly acidic solution, pH3

So3 -> Forms H2SO4, strongly acidic solution, pH1

Question 3

Reaction of Aluminium Oxide & Silicon Oxide with water (product, solution, pH)

Answer 3

Al2O3 -> strong ionic bonds, insoluble in water, pH 7

SiO2 -> strong covalent bonds, insoluble in water, pH 7

Question 4

Why do PCl5, SO3, have higher oxidation numbers?

Answer 4

Empty low-lying 3d orbitals -> used for forming of additional covalent bonds

Question 5

How does nature of bonding affect type of oxide formed?

Answer 5

Ionic bond -> forms basic oxide
Covalent bond -> forms acidic oxide
Polarised ionic bond -> forms amphoteric oxide

Question 6

Why does AlCl3 exist as covalent compound?

Answer 6

1. High charge/size of Al3+ -> high polarising power
2. Cl- has a large ionic radius -> large electron cloud, significantly distorted by Al3+
3. Electron cloud shared between two atoms -> covalent bond