Question

During the change of $O_2$ to $O_2^{-}$ ion, the electron is added to which one of the following orbital?

• A. ${\pi }^{\ast }$ orbitals
• B. $\pi$ orbitals
• C. ${\sigma }^{\ast }$ orbitals
• D. $\sigma$ orbitals

Answer 1

The correct option is A ${\pi }^{\ast }$ orbitals

During change of $O_2$ to $O_2^{-}$ ion, an electron is added to ${\pi }^{\ast }$ orbital.

The configuration of $O_2$ is:

$\sigma \left(1s{)}^2{\sigma }^{\ast }\right(1s{)}^2\sigma \left(2s{)}^2{\sigma }^{\ast }\right(2s{)}^2\sigma \left(2p_z{)}^2\pi \right(2p_x{)}^2\pi \left(2p_y{)}^2{\pi }^{\ast }\right(2p_x{)}^1{\pi }^{\ast }(2p_y{)}^1$

The configuration of $O_2^{-}$ is:

$\sigma \left(1s{)}^2{\sigma }^{\ast }\right(1s{)}^2\sigma \left(2s{)}^2{\sigma }^{\ast }\right(2s{)}^2\sigma \left(2p_z{)}^2\pi \right(2p_x{)}^2\pi \left(2p_y{)}^2{\pi }^{\ast }\right(2p_x{)}^2{\pi }^{\ast }(2p_y{)}^1$