Draw Phosphorous trichloride (PCl3) on some scratch paper and answer the following questions:

Question

PCl3 has ______ bonding electrons

PCl3 has ______ nonbonding electrons

PCl3 has ______ single bonds,______double bonds, and ______ triple bonds

PCl3 has ______ electron geometry and ______ molecular geometry

Answer 1

To draw the Lewis dot structure we would proceed as follows:

P has 5 valence electron

Each Cl has 7 valence electrons (7 x 3 = 21 valence electrons)

Total valence electrons = 21 + 5 = 26 valence electrons to be used

Place P (least electronegative element) in the center and attach 3 Cl atoms (that uses 6 electrons)

Place 3 one pairs of electrons around each Cl atom (that uses another 18 electrons)

Total so far is 24 valence electrons used. Place the remaining 2 electrons on the central P atom as a lone pair

All atoms have 8 electrons (octet) and all atoms have a formal charge of zero. This is the Lewis structure.

6 bonding electrons

2 nonbonding electrons

3 single bonds, 0 double bonds, and 0 triple bonds

tetrahedral electron geometry and trigonal pyramidal molecular geometry