Question

1) Based on their position on the periodic table, which bond do you expect to be the most polar?

Al---P

Al---S

Be--Cl

P--Cl

2) Each scenario describes the properties of a substance. Based on the properties determine if the substance is a Non-acid/Non-base covalent substance, metallic substance, Acid or base covalent substance, or Ionic Substance.

Substance A: Melts at 520 degrees celsius. Decomposes before it can boil. Does not conduct electricity in the solid or liquid state or in aqueous solution.

Substance B: Melts at 157 degrees celsius. Conduct electrcity as a solid and a liquid.

Substance C: Melts at 220 degrees celsius. Does not conduct electricity as a liquid but does when dissolved in water.

Substance D: Melts at 400 degree celsius. Does not conduct electricity as a solid. Does conduct electricity as a liquid and when dissolved in water.

3) Why is the lattice energy of LiF expected to be greater than the lattice energy than NaF?

Answer 1

1) Based on their position on the periodic table, which bond do you expect to be the most polar?

Al---P

Al---S

Be--Cl

P--Cl

A) Be -- Cl bond is more polar as it is a combination of metal and non-metal.

2.

Substance A: Melts at 520 degrees celsius. Decomposes before it can boil. Does not conduct electricity in the solid or liquid state or in aqueous solution = Non-acid/Non-base covalent substance

Substance B: Melts at 157 degrees celsius. Conduct electrcity as a solid and a liquid = metallic substance

Substance C: Melts at 220 degrees celsius. Does not conduct electricity as a liquid but does when dissolved in water = Acid or base covalent substance

Substance D: Melts at 400 degree celsius. Does not conduct electricity as a solid. Does conduct electricity as a liquid and when dissolved in water = Ionic Substance.

3) According to Fajan's rule Smaller cation and larger anion compound has higher lattice energy.

In the LiF and NaF, anoin is same but cations are different.So, smaller cation compound has more lattice energy.