Question

Magnesium oxide is a binary ionic compound. From the formula MgO, how do you know that Mg is the metal?

Answer 1

See below.

Step-by-step explanation:

Method 1:

You know that oxygen is a non-metal.

If the compound is ionic, the oxygen must be combined with a metal.

The Mg must be a metal.

Method 2:

In the formulas of ionic compounds, the positive ion (usually a metal) is written first.