Trends for electron affinity going across the group increases negatively.
Does this mean Noble gases' electron negativity is more negative than halogens?
I'm confuse here.
Noble gases should have a positive electron affinity as adding an electron would make it unstable and thus, will not form.
But for halogens, their attraction for that 1 electron to fill up the $\mathrm{p}$ subshell is very strong.
But according to the theory that electron affinity increase negatively across the period, does this theory has an exception of noble gases?
Next, what about $\ce{Be}$ and $\ce{Mg}$? Their electron affinities are not negative.