Jan 19, 2017

We interrogate the rxn:

${\text{Atom(g)" + Delta rarr "Atom}}^{+} \left(g\right) + {e}^{-}$

#### Explanation:

Now we know that ionization energy INCREASES across a Period from left to right as we face the Table because of the increase in nuclear charge.

Down a Group the ionization energy decreases, because the nuclear charge is effectively shielded by a complete inner shell.

So you can readily solve this so long as you are looking at a Periodic Table. You know that the inert gas neon will have the greatest ionization energy because it has a complete valence shell, and only $\text{d}$ places the gas in top position.

If you are worried about $\text{b}$, then you should, as should any physical scientist, examine the data. See http://www.angelo.edu/faculty/kboudrea/periodic/trends_ionization_energy_fig1.gi

The diagram clearly shows the trend I have argued.