Question

Which atom in Group 1A is expected to lose its one electron the easiest?

A) Lithium (Li)
B) Sodium (Na)
C) Potassium (K)
D) Rubidium (Rb)
E) Cesium (Cs)

Answer 1

Cesium (Cs) is the atom in Group 1A that will lose its electron the easiest, due to low ionization energy derived from its large atomic size.

Step-by-step explanation:

The atom in Group 1A that is expected to lose its one electron the easiest is cesium (Cs). This is based on the periodic trend that as you go down Group 1, the alkali metals, from lithium (Li) to cesium (Cs), the atomic radius increases. This increase in size means that the outermost electron is further away from the nucleus and less tightly held by the nucleus' positive charge, leading to a lower ionization energy. Thus, cesium will lose its electron more readily than the other alkali metals in the same group. Francium (Fr) would technically be the easiest, but it is highly radioactive and exists only in trace amounts, so cesium is generally considered for this type of question.