Ionic Bonding / Covalent Bonding / Types of Substance

Question 1

What would the ionic formulae be for magnesium oxide which contains the ions Mg(2+) and O(2-)?

Answer 1

MgO

one of each ion will balance the charges

Question 2

What would the ionic formulae be for Sodium sulfide which contains the ions Na(+) and S(2-)?

Answer 2

Na(2)S