According to Valence Shell Electron Pair Repulsion (VSEPR) Theory, what is the steric number for selenium dichloride (SeCl_2)?

• A. 5
• B. 3
• C. 2
• D. 4

Answer: (D)

Verified step by step guidance

1. Identify the central atom in selenium dichloride (SeCl_2), which is selenium (Se).
2. Determine the number of atoms bonded to the central atom. In SeCl_2, selenium is bonded to two chlorine atoms, so the number of bonded atoms is 2.
3. Determine the number of lone pairs of electrons on the central atom. Selenium is in group 16, so it has 6 valence electrons. Two of these electrons are used to form bonds with chlorine atoms (one pair per bond), leaving 4 electrons or 2 lone pairs.
4. Calculate the steric number by adding the number of bonded atoms and the number of lone pairs on the central atom: Steric number = number of bonded atoms + number of lone pairs.
5. Use the formula: \(\text{Steric number} = 2 \text{ (bonded atoms)} + 2 \text{ (lone pairs)} = 4\).