Question

Apply molecular orbital theory to predict which species has the strongest bond.

Apply molecular orbital theory to predict which species has the strongest bond.

O+2

O−2

O2

All bonds are equivalent according to molecular orbital theory.

Answer 1

1) Find bond order of O2+

σ and σ* orbital can have maximum of 2 electrons

π and π* orbital can have maximum of 4 electrons

1 O atom have 8 electrons

Here, number of O is 2

so, total number of electrons in O2 is 16

Since charge is +1

Total number of electron = 15

So, total number of electrons to fill is 15

order of filling of orbitals is:

σ1s σ*1s σ2s σ*2s σ2p π2p π*2p σ*2p

Lets fill the orbital

the filled orbital is σ1s2 σ*1s2 σ2s2 σ*2s2 σ2p2 π2p4 π*2p1

Number of electron in bonding orbital = 10

Number of electron in Anti bonding orbital = 5

Bond Order = 0.5*(Number of electron in bonding orbital - Number of electron in Anti bonding orbital)

= 0.5*(10 - 5)

= 2.5

2) Find bond order of O2-

total number of electrons to fill is 17

order of filling of orbitals is:

σ1s σ*1s σ2s σ*2s σ2p π2p π*2p σ*2p

Lets fill the orbital

the filled orbital is σ1s2 σ*1s2 σ2s2 σ*2s2 σ2p2 π2p4 π*2p3

Number of electron in bonding orbital = 10

Number of electron in Anti bonding orbital = 7

Bond Order = 0.5*(Number of electron in bonding orbital - Number of electron in Anti bonding orbital)

= 0.5*(10 - 7)

= 1.5

3) Find bond order of O2

total number of electrons to fill is 16

order of filling of orbitals is:

σ1s σ*1s σ2s σ*2s σ2p π2p π*2p σ*2p

Lets fill the orbital

the filled orbital is σ1s2 σ*1s2 σ2s2 σ*2s2 σ2p2 π2p4 π*2p2

Number of electron in bonding orbital = 10

Number of electron in Anti bonding orbital = 6

Bond Order = 0.5*(Number of electron in bonding orbital - Number of electron in Anti bonding orbital)

= 0.5*(10 - 6)

= 2

Clearly bond order is highest for O2+

So, it forms strongest bond

Answer: O2+