What is an ionic bond? Show the formation of magnesium chloride using electron dot structures, and list two properties of ionic compounds.
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 attraction between oppositely charged ions formed by the transfer of electrons.
2 · Write the configurations. Mg is 2, 8, 2 and loses 2 electrons. Cl is 2, 8, 7 and gains 1 electron.
3 · Draw the electron dot structure. Draw Mg with two crosses and two Cl atoms with seven dots each, with a curved arrow from Mg to each Cl. Then draw [Mg]²⁺ and two [Cl]⁻ ions, each Cl with eight electrons. Write the charges.
4 · Write the ion equations.
Mg → Mg²⁺ + 2e⁻
Cl + e⁻ → Cl⁻, for each of the two chlorine atoms
Mg²⁺ + 2Cl⁻ → MgCl₂
5 · Give two properties.High melting and boiling points; they conduct electricity when molten or dissolved; they dissolve in water but not in kerosene.
6 · Link to real life. Common salt dissolves in water and the solution conducts, so wet hands near switches are dangerous.
7 · Close in one line. So ionic compounds form when metals give electrons to non-metals.
Scoring tip: Show the arrows for electron transfer and the charges on the ions. Missing charges cost the diagram mark.
