When comparing the two elements ga and as , the element with the higher first ionization energy is as based on periodic trends alone?

As has more ionization energy.

Explanation:

Ga is the element of forth period and 13 group.

The electronic configuration is -  

As is the element of forth period and 15 group.

The electronic configuration is -  

Since, As is half filled in 4p orbital it is more stable. Hence, more energy is required to knock out the valence electron.

Hence, As has more ionization energy.

i just learnt this recently but i need to look through my notes again