Question

francium (fr) has the lowest ionization energy in group 1 because - it has the greatest number of protons, so it attracts its electrons the strongest it has the smallest number of valence electrons it has the greatest atomic mass its 1 valence electron is very far from the nucleus, so little energy is needed to remove it

Explanation:

Ionization energy is the energy required to remove an electron from an atom. In Group 1, as we move down the group, atomic size increases. Francium is at the bottom of Group 1. Its out - most valence electron is in a higher energy level, far from the nucleus. The attraction between the nucleus and this valence electron is weak, so less energy is needed to remove it.

Answer:

its 1 valence electron is very far from the nucleus, so little energy is needed to remove it