Question

what is the correct formula for the ionic compound that would result from the combination of sodium and sulfur?

\\(\text{na}_2\text{s}_2\\)
\\(\text{na}_2\text{s}\\)
\\(\text{nas}\\)
\\(\text{nas}_2\\)

Explanation:

Identify the charges of the constituent ions

Sodium (\(\text{Na}\)) is in Group 1 and forms a cation with a \(1+\) charge: \(\text{Na}^+\).
Sulfur (\(\text{S}\)) is in Group 16 and forms an anion with a \(2-\) charge: \(\text{S}^{2-}\).

Balance the charges to achieve neutrality

To balance the \(2-\) charge of one \(\text{S}^{2-}\) ion, two \(\text{Na}^+\) ions are required:

$$ 2(+1) + 1(-2) = 0 $$

Write the chemical formula

Combining two sodium ions and one sulfur ion yields the empirical formula:

$$ \text{Na}_2\text{S} $$

Answer:

• (A) \(\text{Na}_2\text{S}_2\)
• (B) \(\text{Na}_2\text{S}\) (Correct answer)
• (C) \(\text{NaS}\)
• (D) \(\text{NaS}_2\)