According to molecular orbital theory, which of the following is true with respect to Li2+ and Li2-?

🧠 A species is stable if its bond order > 0. A species is unstable if BO ≤ 0.

🗺️ MO analysis:

$\mathrm{Li_2^+}$ (5 electrons): \sigma_{1s}^2\sigma^*_{1s}^2\sigma_{2s}^1 BO = $(3-2)/2 = 0.5 > 0$ → Stable ✓

$\mathrm{Li_2^-}$ (7 electrons): \sigma_{1s}^2\sigma^*_{1s}^2\sigma_{2s}^2\sigma^*_{2s}^1 BO = $(4-3)/2 = 0.5 > 0$ → Stable ✓

⚡ Both ions have BO = 0.5, confirming both are stable (though weakly bound compared to $\mathrm{Li_2}$ with BO = 1).

$\boxed{\text{Answer: Both } \mathrm{Li_2^+} \text{ and } \mathrm{Li_2^-} \text{ are stable}}$