Question

1. which lewis electron - dot diagram is correct for a s²⁻ ion?

Explanation:

Lewis electron - dot diagrams (also known as Lewis structures) for ions show the valence electrons of the atom. Sulfur (S) has 6 valence electrons. When it forms the \(S^{2 - }\) ion, it gains 2 electrons, so it has a total of \(6 + 2=8\) valence electrons. In a Lewis electron - dot diagram for an ion, all the valence electrons are shown as dots (paired or unpaired), and the ion is enclosed in square brackets with the charge indicated outside.

• Option 1: \([\ddot{S}]^{2 - }\) has only 2 pairs of electrons (4 electrons), which is incorrect as \(S^{2 - }\) has 8 valence electrons.
• Option 2: \([:\ddot{S}\cdot]^{2 - }\) has 5 electrons shown (2 pairs and 1 unpaired), which is incorrect.
• Option 3: \([\cdot\ddot{S}\cdot]^{2 - }\) has 4 electrons shown (2 unpaired and 1 pair), which is incorrect.
• Option 4: \([:\ddot{S}:]^{2 - }\) has 8 electrons (4 pairs), which is correct for the \(S^{2 - }\) ion.

Answer:

\([:\ddot{S}:]^{2 - }\) (the fourth option)