Wavelength Chemistry Question

Question

For a He⁺, calculate the wavelength of light (in m) that would be emitted for the orbital transition of n(initial) = 2 to n(final) = 1.

Answer 1

He⁺ has a nuclear charge of 2

∆E = Ef - Ei = Z²R_H (1/nf² - 1/ni²)

∆E = change in energy = ?

Z = atomic number = 2

R_H = -2.179x10^-18 J

n_f = final energy level = 1

n_i = initial energy level = 2

∆E = (2²)(-2.179x10^-18 J) (1 - 0.25)

∆E = -8.716x10^-18 J * 0.75

∆E = -6.54x10^-18 J (minus sign b/c energy is emitted when going from higher to lower energy level)