Which of the following statements is correct regarding the molecule PF_3 and hypervalency?

• A. PF_3 is hypervalent because it contains three fluorine atoms.
• B. PF_3 is not hypervalent because phosphorus follows the octet rule in this molecule.
• C. PF_3 is hypervalent because fluorine can expand its octet.
• D. PF_3 is hypervalent because phosphorus has more than 8 electrons in its valence shell.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the concept of hypervalency. A molecule is considered hypervalent if the central atom has more than 8 electrons in its valence shell, exceeding the octet rule.
2. Step 2: Identify the central atom in PF_3, which is phosphorus (P), and count the number of valence electrons around it. Phosphorus has 5 valence electrons, and each fluorine atom contributes 1 electron through bonding.
3. Step 3: Calculate the total number of electrons around phosphorus in PF_3. Since there are three fluorine atoms bonded to phosphorus, phosphorus shares 3 pairs of electrons (6 electrons) plus its own 5 valence electrons, but in bonding, we consider shared pairs, so phosphorus effectively has 8 electrons around it.
4. Step 4: Recognize that fluorine atoms cannot expand their octet because they are in period 2 and limited to 8 electrons. Therefore, fluorine cannot cause hypervalency in PF_3.
5. Step 5: Conclude that phosphorus in PF_3 follows the octet rule with exactly 8 electrons around it, so PF_3 is not hypervalent.