7.3 Periodic trends in bonding and structure

Question 1

What state are all metals in at room temperature?

Answer 1

Solids (except mercury)

Question 2

Describe metallic bonding

Answer 2

Each atom has donated its negative outer-shell electrons to a sea of delocalise electrons and cations are left behind
Strong electrostatic attraction between cations and delocalised electrons
Giant metallic lattice

Question 3

What are the periodic trends in melting points across period 2 and 3?

Answer 3

• The melting point increases from Group 1 to Group 14 (4)
• There is a sharp decrease in melting point between Group 14 (4) and Group 15 (5)
• The melting points are comparatively low from Group 15 (5) to Group 18 (0)

Question 4

Explain these periodic trends in melting points across period 2 and 3

Answer 4

• Sharp decrease in melting point marks a change from giant to simple molecular structures
• On melting, giant structures have strong forces to overcome so have high melting points. Simple molecular structures have weak forces so lower melting points

Question 5

What elements in periods 2 and 3 have a giant metallic structure?

Answer 5

Li, Be, Na, Mg, Al

Question 6

What elements have a giant covalent structure?

Answer 6

B, C, Si

Question 7

What molecules have a simple molecular structure?

Answer 7

N2, O2, F2, Ne, P4, S8, Cl2, Ar