Question

using the vsepr model, predict the molecular geometry of the polyatomic ion, pf₄⁻. select the single best answer. tetrahedral square planar square pyramidal linear bent octahedral trigonal planar t - shaped trigonal pyramidal seesaw

Explanation:

Step1: Determine central atom

Phosphorus (P) is the central atom in $PF_4^-$.

Step2: Calculate valence - electron pairs

P has 5 valence electrons, each F contributes 7 valence electrons, and there is an extra electron due to the negative charge. So the total number of valence electrons is $5 + 4\times7+ 1=34$. The number of bonding pairs is 4 (P - F bonds), and the number of non - bonding (lone) pairs on P: First, form 4 P - F bonds using 8 electrons. The remaining electrons are distributed around the atoms. The number of electron - pair groups around P is 4 bonding pairs and 0 lone pairs.

Step3: Apply VSEPR model

According to VSEPR, when the central atom has 4 bonding pairs and 0 lone pairs, the molecular geometry is tetrahedral.

Answer:

tetrahedral