Question

What is ground state? What is excited state?

Answer 1

A ground-state atom is an atom in which the total energy of the electrons can not be lowered by transferring one or more electrons to different orbitals.

A excited state is any of the energy levels of a physical system, especially an atom, molecule, etc., that has higher energy than the lowest energy level.

Answer 2

Ground state is the lowest possible energy state an atom can have. Excited state is an energy level that is higher than ground state. :)