The electronic configuration of an atom determines the chemical reactions the atom can participate in, and determines the kinds of molecules that atoms can combine into to form more complicated substances.

What is electron configuration and why is it important?

Electron configurations help make predictions about how certain elements will react. An atom is most reactive when its valence shell is not full and most stable when its valence orbitals are full. Elements that have the same number of valence electrons often have similar properties.

What do electron configurations tell us?

It tells you how many electrons there are in each of the different orbitals (s, p, d, or f) and at which energy level (n= 1, 2, 3, ...).