Stability of the species `Li_(2), Li_(2)^(-), 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) (3+3 = 6) = sigma 1s^(2), sigma 1s^(2) sigma 2s^(2)`
Bond order `= (N_(b)-N_(a))/(2) = (4-2)/(2) = 1`
`Li_(2)^(+) (3+3-1=5) = sigma 1s^(2), sigma 1s^(2) sigma 2s^(1)`
Bond order `= (3-2)/(2) = (1)/(2) = 0.5`
`Li_(2) (3+3+1=7) = sigma 1s^(2), sigma 1s^(2) sigma 2s^(2) , sigma_(2s^(1)`
Bond order `= (4-3)/(2) = (1)/(2) = 0.5`
Stability order is `Li_(2) gt Li_(2)^(+) gt Li_(2)^(-) (because Li_(2)^(-)` has more number of electron in antibonding orbitals which destabilizes the species)