Question

select the correct answer.
which of these elements has four valence electrons?
a. hafnium (hf)
b. radon (rn)
c. silicon (si)
d. sulfur (s)

Explanation:

• Hafnium (Hf): It has 2 valence electrons.
• Radon (Rn): It is a noble gas with 8 valence electrons (full - filled valence shell).
• Silicon (Si): It is in group 14 of the periodic table. The general formula for the number of valence electrons for elements in group \(n\) (where \(n\) is from 1 - 18) is \(n - 10\) (for \(n>10\)). For group 14 (\(n = 14\)), the number of valence electrons is \(4\).
• Sulfur (S): It is in group 16. Using the formula \(n-10\) (where \(n = 16\)), it has 6 valence electrons.

Answer:

C. silicon (Si)