Write Lewis symbols for the following atoms and ions:
Question:

Write Lewis symbols for the following atoms and ions:

$\mathrm{S}$ and $\mathrm{S}^{2-} ; \mathrm{Al}$ and $\mathrm{Al}^{3+} ; \mathrm{H}$ and $\mathrm{H}^{-}$

Solution:

(i) Sand $s^{2-}$

The number of valence electrons in sulphur is 6.

The Lewis dot symbol of sulphur (S) is : $\ddot{s}$ :

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 $[\because{3}:{s}]^{2-}$.

(ii) $\mathrm{Al}$ and $\mathrm{Al}^{3+}$

The number of valence electrons in aluminium is 3 .

The Lewis dot symbol of aluminium (Al) is ${ }^{*} \mathrm{Al}^{\circ}$.

The tripositive charge on a species infers that it has donated its three electrons. Hence, the Lewis dot symbol is $[\mathrm{A}]^{3+}$.

(iii) $\mathrm{H}$ and $\mathrm{H}^{-}$

The number of valence electrons in hydrogen is 1 .

The Lewis dot symbol of hydrogen $(\mathrm{H})$ is $\mathrm{H}$.

The uninegative charge infers that there will be one electron more in addition to the one valence electron. Hence, the Lewis dot symbol is $[\ddot{H}]^{-}$.

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