Question

Write Lewis symbols for the following atoms and ions: \(S\) and \(S ^{2-}\) ; \(Al\) and \(Al ^{3+}\) ; \(H\) and \(H ^-\)

Answer 1

(i) \(S\) and \(S ^{2-}\) 
The number of valence electrons in \(sulphur\) is \(6\). 
The Lewis dot symbol of \(sulphur\) \((S)\) is .
The dinegative charge infers that there will be two electrons more in addition to the six valence electrons. 
Hence, the Lewis dot symbol of \(S ^{2-}\) is .

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(ii) \(Al\) and \(Al ^{3+}\) 
The number of valence electrons in \(aluminium\) is \(3\).
The Lewis dot symbol of \(aluminium\) \((Al)\) is .
The tripositive charge on a species infers that it has donated its three electrons. 
Hence, the Lewis dot symbol is

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(iii) \(H\) and \(H ^-\) 
The number of valence electrons in \(hydrogen\) is \(1\).
The Lewis dot symbol of \(hydrogen\) \((H)\) is  
The uninegative charge infers that there will be one electron more in addition to the one valence electron. 
Hence, the Lewis dot symbol is