Edexcel IGCSE Chemistry F Ionic Bonding Questions

Practise ion formation, ionic formulae, dot-and-cross diagrams, lattice properties and conductivity using charges, tables and particle models.

Exam points

use ion charges from tables or formulae to complete ionic compound formulae
draw or interpret electron-transfer diagrams with correct ion charges and shells
explain melting point and conductivity using giant lattices and mobile ions

Covered syllabus points

1.37 Ion formation 1.38 Common ion charges 1.39 Ionic compound formulae 1.40 Ionic dot-and-cross diagrams 1.41 Ionic bonding 1.42 Giant ionic lattices 1.43 Ionic conductivity

[Maximum number: 6]

This is a question about metals and their compounds.

(a)

In the absence of air, magnesium reacts with sulfur to form the ionic compound magnesium sulfide, MgS

[ 6 ]

(i)

Describe, in terms of electrons, the formation of the ions in magnesium sulfide.

Give the charges on the ions.

[ 3 ]

M1 magnesium (atom) loses two electrons

M2 sulfur (atom) gains two electrons (from magnesium)

M3 charge on magnesium (ion) $2^{+} / \mathrm{Mg}^{2+}$ AND charge on sulfur/sulfide (ion) $\quad 2^{-} / \mathrm{S}^{2-}$

two electrons
transferred from
magnesium (atom) to
sulfur (atom) scores M1
and M2

(ii)

Explain why magnesium sulfide has a very high melting point.

[ 3 ]

M1 strong (electrostatic) force of attraction

M2 between magnesium ions $/ \mathrm{Mg}^{2+}$ and sulfide ions $/ \mathrm{S}^{2-}$ ions

M3 large amount/lot of (heat/thermal) energy needed to overcome forces/attraction

ALLOW strong ionic bonds but No M1 or M2 if between atoms/molecules or any reference to intermolecular forces / covalent bonds

ACCEPT between oppositely charged ions

ACCEPT between positive and negative ions

ACCEPT large amount/lot of (heat/thermal) energy needed to break the bonds

IGNORE more energy

No M3 if reference to overcoming / breaking intermolecular forces / covalent bonds

[Maximum number: 1]

This question is about Group 7, the halogens.

What is the charge on a bromide ion?

[Maximum number: 2]

Sodium hydroxide dissolves in water, forming a strongly alkaline solution.
Ammonia dissolves in water, forming a slightly less alkaline solution.

Ammonium sulfate is used by gardeners as a fertiliser because it contains nitrogen.

Explain why the chemical formula of ammonium sulfate is $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}$ Refer to the charges on the ions in your answer.

M1 ammonium ion is charged $1^{+} / \mathrm{NH}_{4}{ }^{+}$

AND sulfate ion is charged $2^{-} / \mathrm{SO}_{4}{ }^{2-}$

M2 so charges balance/cancel (each other) OWTTE

ALLOW so that ammonium sulfate has no overall charge

M2 not dep on M1

All question bank results loaded

Covered syllabus points

Question 1

Question (a)

Question (i)

Question (ii)

Question 2

Question 3