Question

How to tell if an electron will make a cation or anion

Answer 1

A cation is a positive charged ion and a anion is a negatively charged ion. An electron will make a cation if it is lost and a anion if it is gained.

The etymology of the prefix cat- means the way down: so think of the sun setting down and losing light. Cat = losing electrons (Such as in a CAThode ray).

The etymology of the prefix -an means upwards. So think of the sun rising up and becoming brighter. An = gaining electrons and becoming overall more negative as electrons are negatively charged.