Covalent bonding Flashcards
Which types of element form covalent bonds?
non-metals
How do covalent bonds form?
Electrons are shared between atoms
What is a double covalent bond?
Where two pairs of electrons are shared between atoms
Do covalent compounds have high or low boiling and melting points?
low
Why do covalent compounds have low melting points?
because whilst the covalent bonds are strong, the bonds between molecules are weak and don’t need lots of energy to break them.
Do covalent compounds conduct electricity?
Not usually
Why can’t covalent compounds conduct electricity?
The electrons are fixed in the bond and cannot move to carry charge
What is an allotrope?
Different structural forms of the same element
Name 4 allotropes of carbon
graphite, graphene, diamond and fullerenes
Describe the structure of diamond
Each carbon atom is covalently bonded to 4 other carbon atoms
Describe the properties of diamond
hard, high boiling point, doesn’t conduct electricity
Describe uses of diamond
jewelry and cutting tools
Why does diamond have a high boiling point?
Lots of energy is required to break the strong covalent bonds between atoms
Describe the structure of graphite
Each carbon is covalently bonded to 3 other carbons to form a layer. There are delocalised electrons between the layers
Describe the properties of graphite
soft, conducts electricity
What are the uses of graphite?
electrodes, pencils and lubricants
Why is graphite soft?
The bonds between the layers are weak so can be easily separated
Why can graphite conduct electricity?
The delocalised electrons between the layers can move and carry a charge
describe the bonding in graphene
A single layer of graphite. Each carbon is covalently bonded to 3 others
Describe the properties of graphene
high melting point, very strong, conducts electricity
Describe the properties of fullerenes
carbon atoms are joined to form 3D shapes such as balls or tubes
