Covalent Bonding

Question 1

What is a covalent bond?

Answer 1

When a pair of electrons is shared between two non-metal atoms

Question 2

What is formed from covalent bonds?

Answer 2

Molecules

Question 3

What makes up a simple molecular substance?

Answer 3

Molecules containing a few atoms joined by covalent bonds

Question 4

Explain the properties of simple molecular substances.

Answer 4

• They have low melting and boiling points because they have weak intermolecular forces between molecules which are easy to break
• They don’t conduct electricity because they don’t contain any free electrons or ions

Question 5

(Exam-style question)

Compare the strength of the bonds that hold the atoms in a molecule together with the forces that exist between different molecules.

Answer 5

• The bonds between the atoms in a molecule are strong
• The forces between the molecules are weak

Question 6

When a simple molecular substance melts, is it the bonds between atoms or the forces between molecules that are broken?

Answer 6

The intermolecular forces

(the forces between the molecules)

Question 7

(Exam-style question)

Answer 7

Question 8

(Exam-style question)

Answer 8

Question 9

What type of molecule is poly(ethene)?

Answer 9

Polymer

Question 10

What are polymers?

Answer 10

Large molecules containing chains of covalently bonded carbon atoms

Question 11

What are polymers formed from?

Answer 11

Many small molecules called monomers, when joined together

Question 12

(Exam-style question)

At room temperature and pressure, methane is a gas, while poly(ethene) is a solid.

Suggest why poly(ethene) has a higher boiling point than methane.

Answer 12

• Poly(ethene) molecules are larger than methane molecules
• As molecules get bigger, the strength of the intermolecular forces between them increases
• Therefore, the forces between the molecules are stronger in poly(ethene) than they are in methane and more energy is needed to break them