Write the empirical (or molecular) formulas of compounds that these elements in the third period are expected to form with molecular oxygen and molecular chlorine. (if different oxidation states are possible for an element, write the formula for a highest oxidation state.) in each case indicate whether you expect the compound to be ionic or molecular.

The elements of the third period are sodium (Na), magnesium (Mg), aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), chlorine (Cl), and argon (Ar). The reactions of the metals with nonmetal will make an ionic compound, and the reactions between nonmetals, a molecular compound.

The metals are Na, Mg, and Al. Oxygen and Chlorine are nonmetals.

The reactions with molecular oxygen (O₂) will be:

2Na + O₂ → Na₂O₂ (Ionic)

2Mg + O₂ → 2MgO (Ionic)

2Al + O₂ → Al₂O₂ (Ionic)

Si + O₂ → SiO₂ (Molecular)

P + O₂ → PO₂ (Molecular)

2S + O₂ → 2SO (Molecular)

4Cl + O₂ → 2Cl₂O (Molecular)

Ar + O₂ → NOT REACT (Ar is a noble gas)

The reactions with molecular chlorine (Cl₂) will be:

2Na + Cl₂ → 2NaCl (Ionic)

Mg + Cl₂ → MgCl₂ (Ionic)

2Al + Cl₂ → 2AlCl (Ionic)

Si + Cl₂ → SiCl₂ (Molecular)

P + Cl₂ → PCl₂ (Molecular)

2S + Cl₂ → 2SCl (Molecular)

Cl + Cl₂ → Cl₃⁻ (Molecular)

Ar + Cl₂ → NOT REACT