Stability of the species `Li_(2),Li_(2)^(-) and Li_(2)^(+)` increases in the order of-

Options

A. `Li_(2) lt Li_(2)^(+) lt Li_(2)^(-)`
B. `Li_(2)^(-) lt Li_(2)^(+) lt Li_(2)`
C. `Li_(2) lt Li_(2)^(-) lt Li_(2)^(+)`
D. `Li_(2)^(-) lt Li_(2) lt Li_(2)^(+)`

Answer

B

Explanation

`Li_(2):(sigma_(1s))^(2)(sigma_(1s)^(**))^(2)(sigma_(2s))^(2)`
`Li_(2)^(+):(sigma_(1s))^(2)(sigma_(1s)^(**))^(2)(sigma_(2s))^(1)`
`Li_(2)^(-):(sigma_(1s))^(2)(sigma_(1s)^(**))^(2)(sigma_(2s))^(2)(sigma_(2s)^(**))^(1)`

Greater the bond order, greater is the stability. thus the stability order is: `Li_(2)^(-) lt Li_(2)^(+) lt Li_(2)`
`H=(1)/(2)[7+5-0+0]=6`