Giant Covalent/Macromolecular Structures

Question 1

Define giant covalent structure

Answer 1

3D structure of atoms that are joined by covalent bonds
Eg. Diamond, graphite, silicon IV Oxide

Question 2

Define allotrope

Answer 2

Elements with the same proton number but a different arrangement of atoms

Question 3

Diamond and graphite are allotropes of __________.

Answer 3

Carbon

Question 4

Describe the structure of Diamond

Answer 4

Tetrahedral shape
Each carbon atom is connected to 4 other carbon atoms

Question 5

Describe the properties of diamond

Answer 5

High melting and boiling points - strong covalent bonds throughout the structure
Cannot conduct electricity - all electrons are involved in bonding; no free electrons to carry charge
Hard - strong covalent bonds between atoms. No weak intermolecular forces
Insoluble in water

Question 6

Describe the structure of graphite

Answer 6

Each carbon is bonded to 3 other carbons
The carbon atoms form layers of hexagonal rings
There are weak forces of attraction between the layers
Each carbon atom has one delocalised electron

Question 7

Describe the properties of graphite

Answer 7

Soft - Plates can slide over each other due to the weak Van der Waal’s forces between the plates
Good conductors of electricity - Since only 3 of the 4 valence electrons are involved in bonding, 1 electron is free to carry charge

Question 8

Describe the structure of Silicon IV Oxide

Answer 8

Similar to diamond
Each Si atom is bonded to 4 oxygen atoms

Question 9

Describe the properties of Silicon IV oxide

Answer 9

Hard
Poor conductor of electricity
High melting and boiling points
Insoluble in water