Question

Neglecting electron-electron repulsion what is the energy of a Lithium atom in its ground state? What is the energy of the first excited state of Lithium (also neglecting electron-electron repulsion).

Answer 1

in ground state n = 1

in first excited state n = 2

Li atom atomic number = Z = 3

energy = -2.18 x 10^-18 x Z^2 / n^2

             = -2.18 x 10^-18 x 3^2 / 1^2

             = -1.96 x 10^-17 J

energy in ground state = - 1.96 x 10^-17 J

energy in first excited state = -2.18 x 10^-18 x 3^2 / 2^2

energy in first excited state   = - 4.90 x 10^-18 J