Covalent Bonding

Question 1

What is a covalent bond?

Answer 1

A strong bond that forms when a pair of electrons is shared between two atoms

Question 2

What are the forces of attraction between the molecules?

Answer 2

Very weak

Question 3

To boil or melt a simple molecular compound what do you need to do?

Answer 3

Break the weak intermolecular forces not the covalent bonds

Question 4

What are most molecular substances at room temperature?

Answer 4

Gases or liquids

Question 5

What happens as the molecules get bigger?

Answer 5

The strength of the intermolecular forces increases so more energy is needed to break them, the melting and boiling points increase

Question 6

Do molecular compounds conduct electricity?

Answer 6

No because they don’t have any free electrons

Question 7

What are polymers?

Answer 7

Molecules made up of long chains of covalently bonded carbon atoms

Question 8

How are polymers formed?

Answer 8

When lots of small molecules called monomers join together

Question 9

What are the melting and boiling points in giant covalent structures?

Answer 9

Very high and need lots of energy to break the bonds

Question 10

Do giant covalent structures conduct electricity?

Answer 10

No because they don’t contain charged particles

Question 11

Are giant covalent structures soluble in water?

Answer 11

No

Question 12

What are examples of carbon based giant covalent structures?

Answer 12

Diamond
Graphite
Graphine

Question 13

Properties of diamond.

Answer 13

Made up of a network of carbon atoms that each form four covalent bonds.
High melting point as the bonds take a lot of energy to break.
Strong covalent bonds hold the atoms in a rigid lattice structure making it really hard.
Doesn’t conduct electricity as it has no free electrons or ions.

Question 14

Properties of graphite.

Answer 14

Each carbon atom forms three covalent bonds creating sheets of carbon atoms arranged in hexagons.
No covalent bonds between the layers so they are free to move over each other making it slippy.
High melting point as the covalent bonds in the layers take lots of energy to break.
Only three out of four of carbons outer electrons are used in bonds so it conducts electricity as it has free electrons.

Question 15

Properties of graphine.

Answer 15

Graphine is one layer of graphite.
It is a sheet of carbon atoms joined together in hexagons.
The sheet is just one atom thick making it a two dimensional compound.

Question 16

What are fullerenes?

Answer 16

Molecules of carbon atoms shaped like closed tubes or hollow balls. They are mainly made up of carbon atoms arranged in hexagons but can also contain pentagons or heptagons

Question 17

What can fullerenes be used for?

Answer 17

To cage other molecules. The fullerene structure forms around another atom or molecule which is then trapped inside. This could be used to deliver a drug directly to cells in the body

Question 18

What makes fullerenes good industrial catalysts?

Answer 18

They have a huge surface area

Question 19

What are nanotubes?

Answer 19

Fullerenes. They are like tiny cylinders of graphene so they don’t conduct electricity. They don’t break when stretched so they can be used to strengthen materials without adding much weight.