3.1.3 Bonding

Question 1

What’s a compound?

Answer 1

Atoms of different elements bonded together.

Question 2

What type of force holds ionic substances together?

Answer 2

Electrostatic attraction

Question 3

Do ionic compounds tend to dissolve in water? Why?

Answer 3

• Ionic compounds tend to dissolve in water.

- Water molecules are polar. This means that charged parts pull ions away from the lattice, causing it to dissolve.

Question 4

Solid lead(II) bromide does not conduct electricity, but molten lead(II) bromide does. Explain this with reference to ionic bonding. [3 marks]

Answer 4

• In a solid, ions are held in place by strong ionic bonds.
• When the solid is heated to melting point, the ions gain enough energy to overcome these forces and move…
• …carrying charge (and so electricity) through the substance.

Question 5

Describe how atoms are held together in covalent molecules.

Answer 5

• A covalent bond is the sharing of electrons between atoms, so that the atoms get full outer shells of electrons.
• Both the positive nuclei are attracted electrostatically to the shared electrons.

Question 6

How are the sheets of carbon atoms in graphite held together?

Answer 6

The sheets of carbon atoms in graphite are bonded together by weak van der Waals forces.

Question 7

What is a covalent bond? [1 mark]

Answer 7

A single pair of electrons between two atoms.

Question 8

Explain how a single covalent bond differs from a double covalent bond. [1 mark]

Answer 8

A single covalent bond only contains one pair of shared electrons, whereas a double covalent bond contains two pairs of electrons.

Question 9

What type of structure do diamond and graphite display?

Answer 9

Macromolecular / giant covalent

Question 10

Write down the order of the strength of repulsion between different kinds of electron pairs.

Answer 10

• Lone-pair/lone-pair angles are the biggest
• Lone-pair/bonding-pair angles are the second biggest
• Bonding-pair/bonding-pair angles are the smallest