Question

What is the formula unit for a compound made from Ca and O?

CaO
`{2}` because the total negative charge on O is two.

Ca
`{2}`O because the total negative charge on Ca is one.

CaO because the total positive charge on O is one.

CaO because the total positive charge on Ca is two.

Answer 1

Should be the fourth choice since oxygen is one of the 7 diatomic so it has a 2+/- charge in this case (-)then the Ca cancels it out because it is a 2+ charge

Answer 2

Answer:
`CaO` because the total positive charge on
`Ca` is two.

Step-by-step explanation:

For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.

Here calcium is having an oxidation state of +2 called as
`Ca^(2+)` cation and oxide
`O^(2-)` is an anion with oxidation state of -2. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral
`CaO`.

The cations and anions being oppositely charged attract each other through strong coloumbic forces and form an ionic bond.