Question

what is the principal quantum number that designates the principal electron shell of the atom?

Explanation:

The principal quantum number \( n \) designates the principal electron shell of the atom. It determines the size and energy level of the electron shell. The value of \( n \) can be \( 1, 2, 3,\cdots \). As \( n \) increases, the electron shell is farther from the nucleus and has higher energy.

Answer:

\( n \)