Covalent Bonding

Question 1

What is a covalent bond?

Answer 1

a shared pair of electrons. Both the positive nuclei are attracted electrostatically to the shared electrons. Two shared pairs = double bond etc

Question 2

Simple covalent (molecular) properties

Answer 2

Low melting and boiling points. Doesn’t conduct electricity and is usually a liquid/gas at room temp. Solubility is determined by how polarised the molecule is.

Question 3

Giant covalent (macromolecular) examples

Answer 3

Graphite, diamond, silicon dioxide

Question 4

Graphite

Answer 4

Sheets of C hexagons with delocalised e- (each C forms three bonds with outer e- delocalised)
Weak bonds between layers easily broken so sheets slide over each other - used as dry lubricant
Can conduct electricity - del. e- free to move and carry charge
Low density as layers far apart compared to covalent bond lengths
High melting point (it sublimes) due to strong covalent bonds
Insoluble in any solvent - covalent bonds too strong to break.

Question 5

Diamond

Answer 5

C bonded to four other C in tetrahedral shape
Very high melting point (also sublimes)
Extremely hard
Good thermal conductor as vibrations travel easily through lattice structure
Can’t conduct electricity nor dissolve in any solvent
Structure refracts light (SHINY FINGGG)

Question 6

Dative Covalent bond definition

Answer 6

Where both electrons in electron bonding pair come from one atom. Also known as a coordinate bond.