Oh, Chemistry !!!!!!!!!!?

Question

First, Calculate the wavelength of the light that corresponds to the transition of the electron from the n=4 to n=2 state of the hydrogen atom. Is the light absorbed or emitted??? (1.0967 for transition)


What is the energy of the single electron in a hydrogen atom when it is in the n=4 state??? Is it (-2.178 x 10^ -18 / 16)
Not sure how, though!!!!Explain, please!!!!

Which of the following could be the quantum numbers (n l m(subscript l) m(subscript s) for the valence electron in a potassium atom in its ground state!!!!!! Explain, please!!!

Answer 1

Without considering the fine structure, the electron energy level of the hydrogen atom can be written as:
En = -2.179×10^-18 J/ n^2
Please remember this formula.
Please also memorize the formula between the energy and frequency or wavelength:
E = h•ν = h•c/λ
where E is the energy in joule, h the Plank constant 6.626x10^-34 J•s, ν the frequency in 1/s, c the speed of light 2.998x10^8m/s, and λ the wavelength in m (1nm = 10^-9m).

(1) For n = 4: E4 = -1.362x10^-19 J
For n = 2: E2 = -5.448x10^-19 J
The transition energy ∆E = E4 - E2 = 4.086x10^-19 J
The light is emitted.
λ = h•c/∆E = (6.626x10^-34 J•s)*(2.998x10^8m/s) /(4.086x10^-19 J)
= 4.86x10^-7 m = 486 nm.

(2) you number is correct. Please refer to (1). If you are looking for explanations, see the reference:
http://en.wikipedia.org/wiki/Bohr_model

(3) Every single electron in any atomic orbital are labeled with all four quantum numbers. For example, the valence electron in the outmost atomic orbital of potassium atom is labeled by:
n = 4, l = 0, ml = 0, ms = 1/2.
See following for explanations:
http://en.wikipedia.org/wiki/Quantum_chemistry