* Ionization energy is the amount of energy required to remove one electron from an atom in its gaseous state.

* Anions are negatively charged ions, formed when an atom *gains* an electron.

* Atoms with low ionization energy are more likely to gain an electron to become an anion. This is because their outermost electrons are loosely bound to the nucleus and require less energy to be removed.

In summary: Elements that readily form anions have a strong tendency to gain electrons, which is indicated by their low ionization energy.