What is an ionic bond? Show, with electron dot pictures, the formation of magnesium chloride, and write the ions present in magnesium oxide.
How to lay out the answer. Follow the frame, then write it in your own words.
1 · Define in one line. An ionic bond is the electrostatic attraction between oppositely charged ions, formed by transfer of electrons from a metal to a non-metal.
2 · Write the configurations. Mg (12) is 2, 8, 2 and loses 2 electrons. Cl (17) is 2, 8, 7 and gains 1 electron.
3 · Draw the electron dot picture. Draw Mg with two crosses and two Cl atoms with seven dots each, with an arrow from Mg to each Cl. Then write [Mg]²⁺ and two [Cl]⁻ ions, each Cl with eight electrons.
4 · Write the ion equations.
Mg → Mg²⁺ + 2e⁻
2Cl + 2e⁻ → 2Cl⁻
Mg²⁺ + 2Cl⁻ → MgCl₂
5 · Magnesium oxide. Here Mg gives both electrons to one O atom (2, 6). The ions are Mg²⁺ and O²⁻, both 2, 8: MgO.
6 · Link to real life. Common salt from sea water is an ionic solid of Na⁺ and Cl⁻ ions.
7 · Close in one line. So in an ionic compound every ion reaches a noble gas configuration.
Scoring tip: Show the arrows for moving electrons and the charges on the ions. A dot picture with no charges loses the diagram mark.
