Question

What charge does the barium ion possess in the compound `BaCl_2`?

Answer 1

The Barium ion in this molecule would have `+2` charge.

Explanation:

Barium is in the 6th energy level of the periodic table in the second column, with an electron configuration of `Ba = [Xe] 6s^2`

Barium would lose two electrons to follow the Rule of Octet and become `Ba^+2 = [Kr] 5s^2 4d^10 5p^6`

The Barium ion is `Ba^+2`
The Chloride ion is `Cl^-1`

It takes two `-1` Chloride ions to balance the one `+2` Barium ions to form the Barium Chloride molecule `BaCl_2`

Answer 2

`Ba` commonly forms a divalent ion, i.e. `Ba^(2+)`.

Explanation:

How do I know this? Well, for a start, barium is an alkaline earth metal, that commonly forms a `+II` ion. Even if I didn't know this, I should know that `Br`, a halogen, commonly forms a `-I` ion, and thus barium assumes a `+II` oxidation state in `BaX_2`. Look at their positions on the Periodic Table: `"Group II metal"` and `"Group VII non-metal"`.