Question

draw the lewis dot diagram for a al^{-} anion.

Explanation:

1. Determine the valence electrons of neutral Al atom:

• Aluminum (Al) is in group 13 of the periodic table. The general formula for the number of valence electrons for main - group elements (groups 1 - 2, 13 - 18) is \(n = \text{group number}- 10\) (for groups 13 - 18). For Al (\(\text{group} = 13\)), the number of valence electrons in a neutral Al atom, \(n=3\).

1. Consider the charge of the anion:

• The anion is \(\text{Al}^{-}\). The negative charge (\(-1\)) means that the Al atom has gained 1 extra electron. So the number of valence electrons for \(\text{Al}^{-}\) is \(3 + 1=4\).

1. Draw the Lewis dot diagram:

• Place the symbol of the element (Al) in the center. Then, place dots around the symbol to represent the valence electrons. For \(\text{Al}^{-}\) with 4 valence electrons, we place 4 dots around the Al symbol.

Answer:

\(\text{Al}\cdot\cdot\cdot\cdot\) (where the four dots represent the four valence electrons of the \(\text{Al}^{-}\) anion)