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CHEM 141-04
Fall 2004
Quiz # 4
Name_______________________________
Use the following values in the problems if needed:
c = 3.00 × 108 m/s (speed of light)
h = 6.63 × 10-34 J·s (Plank’s constant)
1. (6 points) Convert 566 nm to hertz (Hz).
566 nm = 566 × 10–9 m = 5.66 × 10–7 m
ν=
ν=
8
3.00 × 10 m / s
5.66 × 10
−7
m
c
λ
= 5.30 × 1014 / s = 5.30 × 1014 Hz
2. (7 points) A photon has a wavelength of 624 nm. Calculate the energy of the photon in
joules.
E = hν =
hc (6.63 × 10−34 J s)(3.00 × 108 m / s)
=
= 3.19 × 10−19 J
−
9
λ
624 × 10 m
3. (6 points) Calculate the wavelength (in nanometers) of a photon emitted by a hydrogen
atom when its electron drops from the n = 5 state to the n = 4 state.
In this problem ni = 5 and nf = 4.
 1
1
∆E = RH 
−
n2
nf 2
 i

 1
1 
 = (2.18 × 10−18 J) 
−
= − 4.91 × 10− 20 J
2
2

4 
5

The sign of ∆E means that this is energy associated with an emission process.
λ=
hc
(6.63 × 10−34 J ⋅ s)(3.00 × 108 m / s)
=
= 4.06 × 10−6 m or 4.06 × 103 nm
−20
∆E
4.91 × 10
J
4. (6 points) An electron in a certain atom is in the n = 2 quantum level. List the possible
values of l and
ml that it can have.
The angular momentum quantum number l can have integral (i.e. whole number)
values from 0 to n − 1. In this case n = 2, so the allowed values of the angular
momentum quantum number are 0 and 1.
Each allowed value of the angular momentum quantum number labels a subshell.
Within a given subshell (label l) there are 2l + 1 allowed energy states (orbitals) each
labeled by a different value of the magnetic quantum number. The allowed values run
from −l through 0 to +l (whole numbers only). For the subshell labeled by the angular
momentum quantum number l = 1, the allowed values of the magnetic quantum number
are −1, 0, and 1. For the other subshell in this problem labeled by the angular momentum
quantum number l = 0, the allowed value of the magnetic quantum number is 0.
BONUS (10 points) Write the ground-state electron configurations for the following
elements: Nitrogen (N, atomic number 7) and Sodium (Na, atomic number 11).
O: 1s22s22p3
Mg: 1s22s22p63s1