Question

Which species has the highest ionization energy? Mg, Mg+, Mg2+, Al+, Al2+

Answer 1

I assume you mean "next ionization energy" (like next electron to be removed) - then i'm going with `Mg^"+2"`

Explanation:

If you take an electron off Mg, `Mg^+`, `Al^+" or`Al^"+2"#, the electron still comes from the valence shell.

However, if you take an electron off `Mg+^"+2"`, this electron comes out of the n=2 shell, or the core electrons. It's ionization energy will be much higher than the other 4 options.

Mg: `**1s^2 2s^2 2p^6** 3s^2`
`Mg^+: **1s^2 2s^2 2p^6** 3s^1`
Al+: `**1s^2 2s^2 2p^6** 3s^2`
Al+2: `**1s^2 2s^2 2p^6** 3s^2`

Mg: `**1s^2 2s^2 2p^6**`

Hope that helps.