FILL IN THE BLANK. The lewis structure of pf3 shows that the central phosphorus atom has nonbonding and bonding electron pair(s)
The Correct Answer and Explanation is :
In the Lewis structure of phosphorus trifluoride (PF₃), the central phosphorus atom has one nonbonding and three bonding electron pairs.
Explanation:
To understand this, we first need to look at the components involved in PF₃. The molecule consists of one phosphorus (P) atom and three fluorine (F) atoms. The phosphorus atom is the central atom because it is less electronegative than fluorine, which is a common approach when drawing Lewis structures.
- Valence Electrons:
- Phosphorus is in group 15 of the periodic table, so it has five valence electrons.
- Each fluorine atom is in group 17 and has seven valence electrons. Since there are three fluorine atoms, they contribute a total of (3 \times 7 = 21) valence electrons.
- In total, PF₃ has (5 + 21 = 26) valence electrons.
- Bonding Electrons:
- The three fluorine atoms each form a single bond with phosphorus. A single bond consists of two electrons (one pair). Therefore, three bonds contribute (3 \times 2 = 6) electrons to the bonding pairs.
- Calculating Nonbonding Electrons:
- After using 6 electrons for bonding, we have (26 – 6 = 20) electrons remaining.
- Since each fluorine atom needs a complete octet (8 electrons), each fluorine atom will use 6 of the remaining electrons (2 from the bond and 6 from nonbonding pairs), accounting for (3 \times 6 = 18) electrons.
- This leaves (20 – 18 = 2) electrons, which will be placed as a nonbonding pair (lone pair) on the phosphorus atom.
- Final Structure:
- In the Lewis structure, the phosphorus atom is surrounded by three bonding pairs with the three fluorine atoms and one lone pair. This gives phosphorus one nonbonding pair and three bonding pairs.
In conclusion, the central phosphorus atom in PF₃ has one nonbonding pair and three bonding pairs, which is essential for understanding its geometry and reactivity. The presence of the lone pair results in a trigonal pyramidal molecular shape, affecting the physical and chemical properties of the molecule.