Question

3. Once magnesium (Mg) gives up electron(s) to become an ion, it will become

Answer 1

Option B. Cation that is smaller than the original atom.

Step-by-step explanation:

Magnesium is a divalent element. This implies that magnesium can give up 2 electrons to become an ion (cation) as shown below:

Mg —> Mg²⁺ + 2e¯

Next, we shall write the electronic configuration of magnesium atom (Mg) and magnesium ion (Mg²⁺). This can be written as follow:

Mg (12) = 2, 8, 2

Mg²⁺ (10) = 2, 8

From the above illustration, we can see that the magnesium atom (Mg) has 3 shells while the magnesium ion (Mg²⁺) has 2 shells.

This simply means that the magnesium ion (Mg²⁺) i.e cation is smaller that the original magnesium atom (Mg).