How are metals named in an ionic compound?

The same as their element name, but we append a number in Roman numerals to indicate the element's oxidation state for elements with variable oxidation numbers, such as the transition metals.

As an illustration, magnesium chloride has its usual name and only needs +2 oxidation number; the same is true for sodium chloride, aluminum chloride, and so on.

But since iron can form +2 or +3 compounds, we must identify the chlorides as iron(II) chloride or iron(III) chloride, respectively, in order to distinguish between them.

Occasionally, we come across outdated terms like ferrous and ferric chloride (iron chlorides) or stannous chloride or stannic chloride (tin chlorides). These are examples of outdated nomenclature, and chemists should no longer use them because IUPAC naming guidelines have been adopted for consistency and to prevent ambiguity.

In an ionic compound, the names of the metals come first, then the nonmetals, whose names have been altered to end in "-ide."