Question

What orbitals are involved in the bonding of PF5? What orbitals are unused.

What orbitals are responsible for the double bonds in CO2? How many pi and how many sigma bonds are there in CO2?

Answer 1

Total number of valecne electrons in PF₅ is 40. ( 5 from P + 7 from each F).

Lewis structure for PF₅ is as follows:

In the above Lewis structure, the central atom P bonded to 5 fluorine atoms. So, the electron groups around the central atom is 5.

According to VSEPR theory, the electron geometry around the central atom which has five electrons groups is trigonal bipyramidal. The hybridization of trigonal bipyramidal geometry is sp³d.

Therefore, the orbitals involved in the bonding of PF₅ is one s, three p, and one d orbitals and the orbitals unused are four d orbitals.

The total number of valence electrons in CO₂ is 16. ( 4 from C + 6 from each O).

The Lewis structure for CO₂ is as follows:

The number electrons groups around the central C atom is 2.

According to VSEPR theory, the electron geometry arouond the cetral atom which has two electron groups is linear. The linear geometry corresponds to the sp hybridization. So, the one s orbital and one p orbital of C involved in hybridization. There are two unhybridized p orbitals on C atoms. Each of these unhybridized p orbitals of C overlap with p orbital of each O by side by side gives two pi bonds.

Therefore, the orbitals responsible for the double bonds in CO₂ are unhybridized p orbitals.

The number of pi bonds is 2 and the number of sigma bonds is 2 in the CO₂ molecule.