What is the Valency of Magnesium?

The valency of Magnesium is 2.

To find the valency, we must look at the atomic structure of Magnesium.

1. Atomic Number: The atomic number of Magnesium is 12. This means it has 12 protons and 12 electrons.
2. Electronic Configuration: We distribute these 12 electrons into shells (K, L, M).
   • 1st shell (K) = 2 electrons
   • 2nd shell (L) = 8 electrons
   • 3rd shell (M) = 2 electrons
   • Configuration = 2, 8, 2.
3. The Octet Rule: Every atom wants a full outer shell of 8 electrons to be stable. Magnesium has 2 electrons in its outermost shell (valence electrons). It is much easier for Magnesium to completely lose those 2 electrons than to find 6 more. By losing these 2 electrons, its combining capacity (valency) becomes 2.

Because electrons carry a negative charge, when Magnesium loses 2 negative electrons, it is left with an excess of 2 positive protons. Therefore, it forms a positive ion (cation) with a charge of +2, written as Mg²⁺.

• Magnesium Oxide (MgO): Oxygen has a valency of 2 (needs 2 electrons). Magnesium gives its 2 electrons directly to Oxygen. They combine in a perfect 1:1 ratio.
• Magnesium Chloride (MgCl₂): Chlorine only needs 1 electron. So, one Magnesium atom will give 1 electron each to two different Chlorine atoms.