2.3 Giant Covalent Structures

Question 1

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

Answer 1

It requires an enormous amount of energy to break down the lattice

Question 2

What element is diamond made of?

Answer 2

Carbon

Question 3

What is the structure of diamonds?

Answer 3

Regular 3D giant structure

Question 4

How many covalent bonds does each carbon atom have?

Answer 4

4

Question 5

Why is diamond hard and transparent?

Answer 5

Because it’s made of carbon atoms that each have 4 covalent bonds

Question 6

Name a similar structured compound to diamond?

Answer 6

Silicon dioxide (silica)

Question 7

How many covalent bonds are between each carbon atom in graphite? Why?

Answer 7

3

Because one of the electrons from each atom becomes delocalised so they only need 3 bonds to fill up the outer shell

Question 8

Describe the structure of graphite

Answer 8

2D flat hexagonal shaped layers

Question 9

Why can the layers in graphite slip over each other?

Answer 9

There are no covalent bonds between the layers and only weak intermolecular forces

Question 10

Why can graphite conduct electricity?

Answer 10

Because one electron from each atom is delocalised, rather like electrons in a metal. The delocalised electrons allow a current to flow so heat and electricity can be conducted easily

Question 11

List 3 properties of giant covalent structures

Answer 11

• very high melting and boiling points
• doesn’t dissolve
• hard appearance

Question 12

How are atoms joined together in giant covalent structures?

Answer 12

Every atom is joined to several other atoms by strong covalent bonds

Question 13

Describe the structure of fullerenes?

Answer 13

Large molecules formed from hexagonal rings of carbon atoms. The rings join together to form cage like shapes with different numbers of electrons, some of which are nanosized

Question 14

Name 4 uses of fullerenes

Answer 14

• drug delivery to the body
• lubricants
• catalysts
• reinforcing materials

Question 15

Give 2 similarities and 2 differences between diamond and graphite

Answer 15

Similarities: giant covalent structures, forms of carbon

Differences: diamond carbon atoms are bonded to 4, graphite carbon atoms are bonded to 3, diamond is hard, graphite is soft

Question 16

Give 2 similarities and 1 difference between graphite and fullerenes

Answer 16

Similarities: forms of carbon, hexagonal rings of atoms

Differences: graphite is a giant structure whereas fullerenes is only a simple molecule