Electrons are found in energy levels around the nucleus of an atom. Energy levels can also be called ""shells."" The energy levels are designated by a principal quantum number (n). The lowest energy level is designated as n=1 whereas the highest energy level is n=7. Which energy level is the closest to the nucleus?

The first electronic shell or energy level, having n = 1, called the K shell, is the closest to the nucleus.

Explanation:

In an atom, the sub atomic particles called electrons, revolve around the nucleus of the given atom at different energy levels, called shells.

The energy levels or the electronic shells are denoted by the principal quantum number (n) and has the following values n = 1, 2, 3, 4, 5, 6, 7; from the innermost shell to the outermost.

The electron shells are also labelled by the alphabets, K, L, M, N, O, P, and Q, from the innermost shell to the outermost.

Thus the first electronic shell having n = 1, called K shell, is the lowest energy level and is present closest to the nucleus.

Whereas, the last electronic shell having n = 7, called Q shell, is the highest energy level and is farthest from the nucleus.