Question

What is the number of electrons in an `Al^(3+)` ion?

Answer 1

The atomic number, `Z`, of aluminum metal is `13`. What is `13-3`?

Explanation:

Clearly, there are 10 electrons associated with a single `Al^(3+)` ion. We don't need any chemistry to make this determination.

The atomic number specifies the number of positively charged particles in the atomic nucleus. The aluminum nucleus contains 13 protons, 13 fundamental, positively charged particles; this is what identifies the nucleus as aluminum. To balance this charge (all matter is neutral after all), there must be also be 13 fundamental negatively charged particles associated with the aluminum nucleus, and what do we call these?