So N has to be a positive whole number. Now, this quantum number, the principal quantum number, designates the shell level or the energy level in which the electron is located. The Larger the n, the Larger Our size or The Larger The Size Of The Atom and The Greater The energy. In other words, an electron found in n equals one is lower in energy than if an electron is found in N equals two. So the higher the n, the greater the size of the atom and the greater the energy level in which our electron is in. The second quantum number is known as the osmic quantum number and is represented by the lowercase cursive l.
Now, this quantum number designates the subshell in which our electron is in.