Giant covalent structures

Question 1

Examples of Giant Covalent Structures

Answer 1

Diamond, silicon and silicon dioxide.

Question 2

Properties of diamond

Answer 2

• A very hard substance
• Poor electrical conductivity
• Very high melting and boiling point

Question 3

Properties of silicon

Answer 3

• Poor conductor of electricity
• Electrical conductivity can be improved by a process known as doping, the addition of small amounts of elements such as phosphorus or boron to pure silicon.

Question 4

Properties of Silicon dioxide (SiO2)

Answer 4

• Very hard substance
• Poor conductor of electricity
• High melting and boiling point

Question 5

Why do giant covalent structures have such high melting and boiling points?

Answer 5

It takes a lot of energy to break the strong covalent bonds between the atoms.

Question 6

What are allotropes?

Answer 6

Allotropes are different forms of the same element in the same physical state.

Question 7

Allotropes of carbon

Answer 7

Graphite, fullerene C60, diamond, graphene

Question 8

Properties of graphite

Answer 8

• Good electrical conductor

- Soft

Question 9

Structure and bonding angle of carbon in graphite

Answer 9

each carbon atom is covalently bonding to 3 other carbon atoms in a 120º angle. Graphite has a layered structure consisting of carbon atoms arranged in hexagonal rings. The layers are held together by LDF. Each carbon atom has a pair of delocalised electrons.

Question 10

What type of structure is fullerene C60?

Answer 10

A simple molecular structure

Question 11

Graphene properties

Answer 11

• very high tensile strength

- high electrical and thermal conductivity.

Question 12

Graphene structure

Answer 12

• A single layer of graphite
• Bond angle of 120º, trigonal planar
• carbon atoms in hexagonal rings