Table of contents

2. Atoms & Elements

Ions

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Multiple Choice

When an atom of magnesium (Mg) loses two electrons, which ion is formed?

Mg^{2+}

Mg^{-1}

Mg^{+}

Mg^{-2}

Verified step by step guidance

Understand that when an atom loses electrons, it becomes a positively charged ion called a cation.

Recall that magnesium (Mg) has an atomic number of 12, meaning it has 12 protons and normally 12 electrons in its neutral state.

If magnesium loses two electrons, the number of electrons decreases from 12 to 10, while the number of protons remains 12.

The charge of the ion is calculated as the difference between the number of protons and electrons: $\text{Charge} = +12 - 10 = +2$.

Therefore, the ion formed is written as $\mathrm{Mg}^{2+}$, indicating a magnesium ion with a +2 charge.

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