4.3 Write Lewis symbols for the following atoms and ions: S and S2–; Al and Al3+; H and H–
(i) S and S2– 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 S2– is .
(ii) Al and Al3+ 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 . (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 .
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