Topic 2 : Ionic Bonding

Question 1

Explain the difference in melting temperature of sodium sulfide being higher than sodium chloride even though both contain ionic bonding (2)

Answer 1

The attractive force between the sodium ion and the anion is greater with sulfide
The sulfide ion has a higher charge (2-) than the chloride ion (1-).

Question 2

Explain how changes in the cation affect the bond strength in an ionic compound (look at pink question booklet for table) (2)

Answer 2

Higher charge on the cation so a stronger attraction between ions
2+ cation in CaF2 compared to a 1+ cation in LiF and KF
Smaller the radius of the cation, the stronger the attraction between ions
Li+ is smaller than K+

Question 3

State the meaning of the term ‘ionic bond’ (2)

Answer 3

Strong electrostatic attraction between oppositely charged ions

Question 4

State the conditions for an ionic compound to conduct electricity (1)

Answer 4

When molten or dissolved in water (aqueous solution)

Question 5

Draw a labelled diagram of electrolysis apparatus to investigate for the presence of ionic bonding

Answer 5

See book

Question 6

Give the formula of a stable ion that is isoelectronic with Mg2+ (1)

Answer 6

O2-

Question 7

What is meant by isoelectronic ions?

Answer 7

Isoelectronic ions have the same electronic configuration

Question 8

Why does the ionic radius decrease for the isoelectronic ions N3- to Al3+? (2)

Answer 8

Increase in number of protons in the nucleus so increases the attractions for the electrons

Question 9

Deduce the order of increasing size of ions : Br-, Ca2+, Cl- , K+ (4)

Answer 9

Ca2+, Cl- and K+ are isoelectronic with one another

Br- has one more shell of electrons than the others so it is the largest

From Cl- to K+ to Ca2+ there are more protons in the nucleus

Order is

Ca2+ < K+ < Cl- < Br-