What is the ground-state electron configuration of O2-? A (σ2s)2(σ2s*)2(σ2p)2(π2p)4(π2p*)1(π2p*)1 B (σ2s)2(σ2s*)2(π2p)4(π2p*)1 C (σ2s)2(σ2s*)2(σ2p)2(π2p)3(π2p*)2(π2p*)2 D (σ2s)2(σ2s*)2(σ2p)2(π2p)4(π2p*)2(π2p*)1

The ground state electron configuration of O2- is Choice C: (σ2s)2(σ2s*)2(σ2p)2(π2p)3(π2p*)2(π2p*)2

Discussion:

The molecular orbital configuration is dependent on the number of electrons involved in the molecule.

These are all written into various molecular orbitals as described in the Aufbau principle of electron configuration.

Since O2 contains 16 electrons, when it gains an electron to become O2-;

O2^- contains 17 electrons.

Its molecular orbital configuration is;

It is noteworthy to remember that the inner (σ1s)2 and (σ1s*)2 are represented as KK. This inner shell does not take part in bonding.

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(σ2s)2(σ2s*)2(σ2p)2(π2p)4(π2p*)2(π2p*)1

Explanation:

In writing molecular orbital configuration, the number of valence electrons involved in the molecule are all written into  various molecular orbitals in accordance with the Aufbau principle.

O2^- contains 17 electrons. Its molecular orbital configuration is KK(σ2s)2(σ2s*)2(σ2p)2(π2p)4(π2p*)2(π2p*)1. Recall that the inner (σ1s)2 and (σ1s*)2 is designated as KK. This inner shell does not take part in bonding. The bond order in O2^-  is 1.5.

22,600 J or 22.6 kJ

Explanation: