Topic 1 - Key concepts in chemistry - Types of substances (1.32 - 1.42)

Question 1

Ionic bonding definition

Answer 1

When electrons are transferred from metal atom(s) to non metal atom(s). Strong electrostatic forces occur between oppositely charged ions

Question 2

Covalent bonding defintion

Answer 2

When pair(s) of electrons are shared between two or more non metal atoms. Strong bonds are created

Question 3

metallic bonding definition

Answer 3

strong electrostatic bonds between metal cations surrounded by a sea of delocalised electrons

Question 4

how many covalent bonds do carbon atoms have in diamond

Answer 4

4

Question 5

how many covalent bonds do carbon atoms form in graphite

Answer 5

3

Question 6

why does diamond have a high melting point

Answer 6

strong covalent bonds between layers take lots of energy to break

Question 7

why is graphite slippery

Answer 7

no covalent bonds between layers so they are only held together weakly. layers can slide over each other, making it a good lubricant

Question 8

why is diamond hard

Answer 8

strong covalent bonds hold diamond in a rigid lattice structure, making it really hard.

Question 9

why doesnt diamond conduct electricity

Answer 9

no free electrons or ions to carry the charge

Question 10

why does graphite conduct electricity

Answer 10

only 3 out of 4 carbon outer electrons are used in bonds, so one delocalised electron is available to carry the electric charge.

Question 11

Explain the strength, conductivity and melting point of fullerenes

Answer 11

• Weak forces between molecules do not require a lot of energy to overcome these.
• Therefore has a low melting point
• Fullerene only conducts electricity on the surface of the molecule as there is no-to-little electron movement therefore it cannot conduct electricity that well
• Molecular structure