Periodicity

Question 1

State and explain how melting and boiling points change from Na to Al.

Answer 1

Melting point increases

Increase in ionic charge

More delocalised electrons

Stronger attraction between metal cations and delocalised electrons

More energy needed to break bonds

Question 2

State and explain how melting points change across period 3, from Na to Ar.

Answer 2

Group 14 - highest melting point - giant covalent lattices

Strong covalent bonds between atoms

Lots of energy is needed to break the bonds

Group 15 onwards - simple molecular

Weak London forces between molecules

Little energy needed to break the bonds

Strength of London forces depends on no. of e-
S8>P4>Cl2>Ar

Question 3

What is Li, Be, B, Na, Mg, Al’s structure and what is the attraction between particles?

Answer 3

Their structure is giant metallic and has strong electrostatic attraction between metal cations and delocalised electrons.

Question 4

What is Si and C’s structure and what is the attraction between particles?

Answer 4

Their structure is giant ionic and has strong electrostatic attraction between ions.

Question 5

What is N, O, F, Ne, P, S, Cl, Ar’s structure and what is the attraction between particles?

Answer 5

Their structure is simple molecular / covalent structures and has weak London forces between molecules.