What does the notation 2s2 mean?

Answer 1

The notation (2s^2) refers to an electron configuration, specifically indicating that there are two electrons in the 2s subshell of an atom. In this context, "2" denotes the principal quantum number (the energy level), while "s" indicates the type of subshell. The superscript "2" signifies that there are two electrons occupying that subshell, which can hold a maximum of two electrons. This notation is commonly used in chemistry to describe the distribution of electrons in an atom's orbitals.