Question

How does a barium atom become a barium ion with a `2^+` charge?

Answer 1

See explanation below.

Explanation:

Basically, an atom becomes an ion when it "steals" electrons from another atom or when another atom "steals" electrons from it. Barium becomes an ion with a `2^+` charge when it reacts with another atom of another element that steals 2 electrons from it.

For instance, in the reaction represented below, solid barium reacts with hydrochloric acid to produce aqueous barium chloride and hydrogen gas: `Ba_((s)) + 2HCl_((aq)) -> BaCl_(2(aq)) + H_(2(g))`
In this redox reaction, barium starts as a neutral solid but becomes an aqueous ion with a `2^+` charge. Hydrogen begins as an aqueous ion with a `1+` charge and becomes a neutral gas. Thus, two hydrogen atoms steal a total of two electrons from one barium atom, resulting in the formation of neutral hydrogen gas and a barium ion with a `2^+` charge.

An atom is oxidized when it has one or more electrons stolen from it.
An atom is reduced when it steals one or more electrons from another atom.