Question

which of the following elements has the lowest ionization energy? c ne f na rb

Explanation:

Ionization energy is the energy required to remove an electron from an atom. In the periodic table, ionization energy generally increases across a period (from left to right) and decreases down a group. Among the given elements:

• \(C\) (carbon) is in period 2, group 14.
• \(Ne\) (neon) is a noble gas in period 2, group 18 (has a full - shell electron configuration, very high ionization energy).
• \(F\) (fluorine) is in period 2, group 17.
• \(Na\) (sodium) is in period 3, group 1.
• \(Rb\) (rubidium) is in period 5, group 1.

Since \(Rb\) is the furthest down the group (has the largest atomic radius among the options, and the outermost electron is the most loosely held), it will have the lowest ionization energy.

Answer:

Rb