Ap Chemistry Worksheet - Dr. Kathleen Gorski, Wilbraham And Monson Acaddemy Page 13
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246.23 (a) Calculate the energy of a photon of electromagnetic radiation whose frequency is 6.74 x
12
-1
10
s
. (b) Calculate the energy of a photon of radiation whose wavelength is 322 nm. (c)
-18
What wavelength of radiation has photons of energy 2.87 x 10
J.
6.38 (a) Calculate the energies of an electron in the hydrogen atom for n = 1 and for n = ∞. How
much energy does it require to move the electron out of the atom completely (from n = 1 to n =
∞), according to Bohr? Put your answer in kJ/mol. (b) The energy for the process H + enery
+
-
! H
+ e
is called the ionization energy of hydrogen. The experimentally determined value
for the ionization energy of hydrogen is 1210 kJ/mol. How does this compare to your
calculation?
6.56 For the table that follows, write which orbital goes with the quantum numbers. Don’t worry
about x, y, z subscripts. If the quantum numbers are not allowed, write “not allowed.”
n
l
m
Orbital
l
2
1
-1
2p (example)
1
0
0
3
-3
2
3
2
-2
2
0
-1
0
0
0
4
2
1
5
3
0
6.66 What is the maximum number of electrons in an atom that can have the following quantum
numbers: (a) n = 2, m
= -½, (b) n = 5, = 3, (c) 2s, (d) 4f?
l
6.69 Write the condensed electron configurations for the following atoms, using the appropriate
noble-gas core abbreviations: (a) Cs, (b) Ni, (c) Se, (d) Cd, (e) U, (f) Pb.
[6.87] Bohr’s model can be used for hydrogen-like ions—ions that have only one electron, such as
+
2+.
+
He
and Li
(a) Why is the Bohr model applicable to He
ions but not to neutral He atoms? (b)
+
2+
The ground-state energies of H, He
, and Li
are tabulated as follows:
+
2+
Atom or ion
H
He
Li
-18
-18
-17
Ground-state energy
-2.18 x 10
J
-8.72 x 10
J
-1.96 x 10
J
By examining these numbers, propose a relationship between the ground-state energy of
hydrogen-like systems and the nuclear charge, Z. (c) Use the relationship you derive in part (b)
5+
to predict the ground-state energy of the C
ion.
6.97 Microwave ovens use microwave radiation to heat food. The energy of the microwaves is
absorbed by water molecules in food and then transferred to other components of the food. (a)
Suppose that the microwave radiation has a wavelength of 11.2 cm. How many photons are
required to heat 200 mL of coffee from 23 °C to °60 C? (b) Suppose the microwave’s power is
900 W . How long would you have to heat the coffee in part (a)?
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