Covalent Bonding

Question 1

How do molecules form?

Answer 1

Molecules form when two or more atoms bond together

Question 2

How are molecules held together?

Answer 2

Molecules are held together by strong covalent bonds

Question 3

What does a single covalent bond contain?

Answer 3

A shared pair of electrons

Question 4

What happens in covalent bonding?

Answer 4

In covalent bonding, two atoms share electrons, so they’ve both got a full outer shell of electrons. Both the positive nuclei are electrostatically attracted to the shared electrons

Question 5

Do atoms just form single bonds?

Answer 5

Atoms don’t just form single bonds - double and triple covalent bonds can be formed between atoms too

Question 6

What are giant covalent structures?

Answer 6

Giant covalent structures contain a huge network of covalently bonded atoms. They’re sometimes called macromolecular structures

Question 7

What atoms can form a giant covalent structure?

Answer 7

Carbon atoms - this is because they each can form four strong covalent bonds

Question 8

Explain the structure of graphite

Answer 8

The carbon atoms are arranged in sheets of flat hexagons covalently bonded with 3 bonds each. The fourth outer electron of each atom is delocalised. The sheets of hexagons are bonded together by weak van der Waals forces

Question 9

How does the structure of graphite explain its properties?

Answer 9

1. The weak bonds between the layers of graphite are easily broken so the sheets can slide over each other
2. The ‘delocalised’ electrons are free to move along the sheets carrying charge
3. The layers are quite far apart compared to the length of the covalent bonds, so graphite has a low density
4. The strong covalent bonds give graphite a high melting point
5. It is insoluble in any solvent because the covalent bonds are too strong to break

Question 10

What is the structure of diamond?

Answer 10

Diamond is made up of carbon atoms. Each carbon atom is covalently bonded to four other carbon atoms. The atoms arrange themselves in a tetrahedral shape

Question 11

Explain the properties of diamond

Answer 11

1. It has a very high melting point because of the strong covalent bonds
2. It is extremely hard
3. Vibrations travel easily through the stiff lattice, so it’s a good thermal conductor
4. There is no delocalised electrons so it can’t conduct electricity
5. It won’t dissolve in any solvent because the covalent bonds are too strong to break
6. You can cut diamond to form gemstones - it refracts a lot of light so it sparkles

Question 12

What is dative covalent bonding?

Answer 12

Dative covalent bonding is where both electrons come from one atom

Question 13

Give an example of dative covalent bonding

Answer 13

The ammonium ion is an example of dative covalent bonding. It forms when the nitrogen atom in an ammonia molecule donates a pair of electrons to a proton

Question 14

What is dative covalent bonding also called?

Answer 14

Coordinate bonding