Quantum Numbers: Size of An Atom

[Sean Sugai 4E]

The state of an electron is defined by n, l, Ml, and Ms. Why does the size of an atom increase as n increases?

[zoedfinch1K]

If you think about what n, represents, it is the shell of an atom. When the shell is increasing, there are now a great number of electrons (or places where electrons could be). In a neutral atom, the number of protons and electrons are the same so this increase in electrons correlates to an increase in protons, therefore making the nucleus of the atom larger. With a larger nucleus and electron "cloud", the atom will be bigger.

[KSong_1J]

n is related to the size and energy of the orbital; as n (aka the energy level) increases, the mean distance of an electron from the nucleus increases, which means the radius of the atom gets larger.

[John Arambulo 1I]

The reduced electrostatic attraction due to the distance from the nucleus, electron-electron repulsions, and shielding from the inner energy levels and subshells results in an effective nuclear charge, and the result is an increase in the size of the atom.

[britthanul234]

N is the size and energy of the orbital. As n increases, the distance from nucleus increases, so the size (radius) increases as well.