Which element has the electron configuration [Ne] 3s^2?

The element with the electron configuration [Ne] 3s^2 is magnesium. In this notation, [Ne] represents the electron configuration of neon, which accounts for the first 10 electrons. The additional 2 electrons in the 3s subshell give magnesium a total of 12 electrons (10 from neon plus 2 from the 3s subshell). This is consistent with magnesium’s position in the periodic table as the element with atomic number 12.

This configuration indicates that magnesium is in Group 2, which is characteristic of alkaline earth metals. The two electrons in the outermost 3s subshell are responsible for its chemical properties, including its tendency to lose these electrons to form Mg²⁺ ions.

Other elements listed have different configurations:

• Aluminum has the electron configuration [Ne] 3s^2 3p^1, indicating it has one additional electron in the 3p subshell.

• Potassium, with an atomic number of 19, would have the electron configuration [Ar] 4s^1, reflecting its higher energy level with one electron in the 4s subshell.

• Calcium, which has an atomic number of 20, has the configuration [Ar]