Question

How does an ionic bond form?

Answer 1

It's a matter of one atom donating an electron (or more) to another.

Explanation:

Let's take sodium `Na` that has one electron in its outer shell. Losing it, would mean that it would have the 'sacred' inert-gas configuration (full outer shell, just like Neon).
Now we have fluorine `F`. It has 7 electrons in its outer shell. If it could have just one more, it would also reach the Neon-status.

They clinch the deal, but now `Na` has become `Na^+` (it's positively charged, because there is one electron short for compensating the charge of the nucleus).
And `F` becomes `F^-` for having one too many.
These charged atoms are called ions .

And since opposites attract, `Na^+` and `F^-` tend to stick together, in what we call an ionic bond. And a salt (sodium fluride) has formed.