Question

practice writing binary ionic formula examples:

1. magnesium + chlorine
2. aluminum + oxygen
3. calcium + chlorine
4. lithium + oxygen
5. calcium + oxygen

Explanation:

Step1: Determine the ions

• Magnesium (\(Mg\)) forms \(Mg^{2+}\) ion, chlorine (\(Cl\)) forms \(Cl^{-}\) ion.
• Aluminum (\(Al\)) forms \(Al^{3+}\) ion, oxygen (\(O\)) forms \(O^{2 -}\) ion.
• Calcium (\(Ca\)) forms \(Ca^{2+}\) ion, chlorine (\(Cl\)) forms \(Cl^{-}\) ion.
• Lithium (\(Li\)) forms \(Li^{+}\) ion, oxygen (\(O\)) forms \(O^{2 -}\) ion.
• Calcium (\(Ca\)) forms \(Ca^{2+}\) ion, oxygen (\(O\)) forms \(O^{2 -}\) ion.

Step2: Use the criss - cross method

• For \(Mg^{2+}\) and \(Cl^{-}\): \(MgCl_{2}\) (criss - cross \(2\) from \(Mg^{2+}\) to \(Cl\) and \(1\) from \(Cl^{-}\) to \(Mg\), and \(1\) is omitted).
• For \(Al^{3+}\) and \(O^{2 -}\): \(Al_{2}O_{3}\) (criss - cross \(3\) from \(Al^{3+}\) to \(O\) and \(2\) from \(O^{2 -}\) to \(Al\)).
• For \(Ca^{2+}\) and \(Cl^{-}\): \(CaCl_{2}\) (criss - cross \(2\) from \(Ca^{2+}\) to \(Cl\) and \(1\) from \(Cl^{-}\) to \(Ca\), and \(1\) is omitted).
• For \(Li^{+}\) and \(O^{2 -}\): \(Li_{2}O\) (criss - cross \(2\) from \(O^{2 -}\) to \(Li\) and \(1\) from \(Li^{+}\) to \(O\), and \(1\) is omitted).
• For \(Ca^{2+}\) and \(O^{2 -}\): \(CaO\) (criss - cross \(2\) from \(Ca^{2+}\) to \(O\) and \(2\) from \(O^{2 -}\) to \(Ca\), and they cancel out).

Answer:

1. \(MgCl_{2}\)
2. \(Al_{2}O_{3}\)
3. \(CaCl_{2}\)
4. \(Li_{2}O\)
5. \(CaO\)