H Study Guide Ch.4 & 25
1.
234
90
Th 
234
91
2.
210
83
Bi 
0
−1𝑒
3.
234
91
Pa* 
4.
10
5
B + 01 n 
5.
14
6
C 
6.
234
91
7.
23
12
8.
210
82𝑃𝑏
14
7
234
91
→
+
7
3𝐿𝑖
gama decay
4
2
He
+
+
4
2
4
2
neutron bombardment resulting in alpha decay
beta decay
0
−1𝑒
19
10𝑁𝑒
+
beta decay
Pa + 00𝛾
230
89𝐴𝑐
0
−1𝑒
beta decay
0
−1𝑒
+ 210
84𝑃𝑜
N +
Pa 
Mg 
Pa +
He
He + 00 
alpha decay
alpha decay w/gamma emission
210
83𝐵𝑖
9. The neutron to proton ratio that correlates with the band of stability. Radioactivity results when unstable
nuclei emit energy in order to gain stability.
10. Fusion gives off more energy. Nuclear reactions give off more energy.
Ch 4
36. Charge= -1; mass= 9.11 x10-28g
37. Strengths: Rutherford’s model explained the results of the gold-foil experiment and why an atom is electrically
neutral. Weakness: the model could not account for the total mass of an atom or the arrangement of the electrons.
38. Protons and neutrons; net positive charge equal to the number of protons
39. attraction to the positively charged nucleus
41. the plum pudding model
42. the α particles were deflected by the positively charged gold nuclei
43. protons and neutrons
44. they are all equal
46. the number of positively charged protons equals the number of negatively charged electrons
48. differ: number of neutrons, masses; similar: chemical properties, number of protons and electrons
50. the superscript represents the mass number (40) and the subscript represents the atomic number (19)
51. number of n0 = mass number – atomic number
56.
Particle
α
β
γ
Symbol
4
He
2
0
β
−1
0
γ
0
Mass (amu)
4
Charge
+2
1/1840
-1
0
0
57. α, mass number decreases by 4; β, no change in mass number; γ, no change in mass number
62. mass number is 200
64a.
132
Cs, e- =55, p+ =55, n0 =77
55
65a. Ga-64, e- =31, p+ =31, n0 =33
68. 51.99 amu (52.0 amu with sf)
82.
28
Si
14
29
Si
14
30
Si
14
Ch.25
35. 1. Atoms; 2. Stable; 3. Unstable; 4. Do not decay; 5. -9. Alpha decay, beta decay, gamma emission, electron
capture, positron emission
37. nuclear reactions release more energy per mole. Nuclear reactions incolve neutrons and protons, whereas
chemical reactions involve electrons
38. a: 2, 4, 5; b: 1; c: 3,6
42. the strong nuclear force binds nucleons together
48. transmutation is the changing of an atoms nucleus such that a new element is formed. Most, but not all nuclear
reactions are transmutations
50. radioactive, short half-lives, alpha emitters
54. difference between mass of the nucleon’s summed separately and the actual mass of the nucleus
57. a chain reaction occurs when a reaction produces one or more of the particles needed as a reactant. An
example is the fission of U-235 by absorption of a neutron
79. 9.2 half-lives; 0.625 mg