The main group elements that have three unpaired electrons are those in the nitrogen group, specifically phosphorus (P) and arsenic (As). These elements belong to group 15 of the periodic table.
To understand why these elements have three unpaired electrons, we can look at their electron configurations. Phosphorus has an atomic number of 15, and its electron configuration is [Ne] 3s² 3p³. In this configuration, you can see that the 3p subshell has three electrons that are unpaired: one in each of the three p orbitals.
Similarly, arsenic, which has an atomic number of 33, has the electron configuration [Ar] 4s² 3d¹⁰ 4p³. Like phosphorus, the 4p subshell contains three unpaired electrons. The presence of these unpaired electrons allows these elements to readily form bonds and participate in chemical reactions, making them quite versatile.