Ionic bonding in magnesium oxide

3 marks · Easy

The table shows the number of electrons in neutral atoms and the corresponding ions for magnesium and oxygen.

Particle	Number of electrons
Mg atom	12
Mg^{2+} ion
O atom	8
O^{2-} ion

(a)

Complete the table by filling in the missing numbers for the ions.

[2 marks]

(b)

Explain, in terms of electron transfer, how these ions form.

[1 mark]

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

Show answer

(a) Mg^{2+}: 10 electrons; O^{2-}: 10 electrons · must show Mg^{2+} = 10; O^{2-} = 10

(b) Mg atom loses 2 electrons to form Mg^{2+}; O atom gains 2 electrons to form O^{2-} · must show reference to Mg losing 2 electrons, O gaining 2 electrons

Common mistakes: Filling values as same as atoms

Show mark scheme and worked solution

Marking points

B1 (a) · 1 mark · Mg^{2+} ion: 10 electrons entered correctly.

B1 (a) · 1 mark · O^{2-} ion: 10 electrons entered correctly.

B1 (b) · 1 mark · Explains Mg loses 2 electrons and O gains 2 electrons to form ions.

Worked solution

Particle	Number of electrons
Mg atom	12
Mg^{2+} ion	10
O atom	8
O^{2-} ion	10

Magnesium loses 2 electrons to form Mg^{2+}, oxygen gains 2 electrons to form O^{2-}.