Physics 110
Physical Science
Name _______________
Date ________________
Final
Must-Know-How-to-Do Problems
Make sure you check units and significant figures.
Planck’s Constant h = 6.637x10–34 J1 ev = 1.6x10–19 J
Atomic Physics
1. The human eye is most sensitive to yellow green light of frequency 5.45x1014
Hz. What is the energy in joules of a photon of light at this frequency?
E = hf
= (6.63x10–34)(5.45x1014)= 3.61x10–19 J
Table 1
2. Using Table 1, if a hydrogen atom is in the n=3
–0.85
state and it drops back to the ground state (n=1).
–1.51
Energy,
a. What is the energy that is lost, in ev and J?
–19
in ev –3.40
12.09 ev = 1.93x10 J
b. What is the frequency of the photon that is
emitted?
E = hf, f=E/h = 1.93x10–19/6.63x10–34 = 2.91x10–14 Hz
n =4
n=3
n=2
n=1
–13.60
c (Review) What is the wavelength of the photon?
c = λf, λ = c/f = 3x108/2.91x1014 = 1.03x10–6 m
Nuclear Physics
3. Fill in this table
Symbol
Protons
B
9
Neutrons
10
Electrons
Mass Number
6
18
11
40
4. A radioactive sample has an active of 160 counts per minute that drops to 10
cpm in 24 minutes. What is its half-life?
80-40-20-10 t1/2 = 8 minutes
1
Physics 110
Physical Science
Name _______________
Date ________________
5. Complete the following nuclear reaction equations:
4
14
17
2 He  7 N  8 O  _______
1
0
28
n 14
Si  _______ 11H
8
5
B  _______  10 e
What is the particle
0
1
e called when emiited in radioactive
decay?
210
84
Po 206
82 Pb  ______
6.
238
92
What is the emitted particle called?
U has how many neutrons?
7. Which of these atomic elements has the greatest atomic size?
a. lithium (Li)
b. fluorine (F)
c. potassium (K)
d. bromine (Br)
8. Referring only to a periodic table and recalling the octet rule, give the number
of valence electrons expected for
a) sulfur (S)
b) neon (Ne)
c) bBromine (Br)
d) nitrogen (N)
e) carbon (C)
2