7.3 Periodic Trends in Bonding and Structure

Question 1

What is metallic bonding? Required.

Answer 1

• The strong electrostatic attraction between cations and delocalised electrons

Question 2

What structure do metals have?

Answer 2

• They all have a giant metallic lattice structure

Question 3

What are the properties of metals?

Answer 3

• High electrical conductivity
• High melting and boiling points

Question 4

When can metals conduct electricity, and how?

Answer 4

• When in the solid or liquid states
• This is because the delocalised electrons are free to move through the structure and carry charge

Question 5

Why do most metals have high melting and boiling points?

Answer 5

• Large amounts of energy are needed to overcome the strong electrostatic attraction between the cations and electrons

Question 6

Are metals soluble? Why?

Answer 6

• No
• They react with solvents instead, such as group 1 metals with water

Question 7

What are giant covalent lattices? Required.

Answer 7

• Networks of atoms bonded by strong covalent bonds

Question 8

List 2 elements that form giant covalent lattices.

Answer 8

• Carbon
• Silicon

Question 9

What are the melting and boiling points of giant covalent lattices like, and why?

Answer 9

• They are high because a lot of energy is needed to break the strong covalent bonds

Question 10

Are giant covalent lattices soluble? Why?

Answer 10

• No
• The covalent bonds are too strong to be broken due to interactions with the solvent

Question 11

Can giant covalent lattices conduct electricity? Why?

Answer 11

• Most aren’t as they don’t have any electrons that are free to conduct electricity
• Graphite and graphene are exceptions to this as they only use 3 of their 4 electrons in their outer shell to form covalent bonds

Question 12

What is the difference between graphite and graphene?

Answer 12

• Graphene is a single layer of graphite (in graphite the separate layers are bonded together by weak London forces)

Question 13

How do melting points vary across periods 2/3?

Answer 13

• The melting points increase from periods 1 to 4
• There is a sharp decrease between groups 4 and 5
• From group 5 to 0, the melting points are low

Question 14

Why do melting points decrease between groups 4 and 5?

Answer 14

• The elements change from giant molecular structures to simple molecular substances

Question 15

Why do melting points increase between groups 1 and 3?

Answer 15

• The larger the charge of the cation (and therefore also the relative amount of delocalised electrons) the stronger the metallic bonds