Calculate energy in joules required to move an electron from its ground state to an excited state

Question

Calculate the energy in joules required to move an electron from its ground state (level 1) to an excited state of n=[2].

Answer 1

∆E = Z²R_H (1/n_f² - 1/n_i²) where

∆E = change in energy in joules

Z = nuclear charge (assumed to be 1, i.e. hydrogen, since no element was stated)

R_H = -2.179x10^-18 J

n_f = final energy level = 2

n_i = initial energy level =1

∆E = -2.179x10^-18 J (1/4 - 1) = -2.179x10^-18 J x -0.75

∆E = 1.63x10^-18 J