Download Name - Net Start Class

Chapter 28 Review Sheet Key
1) What is an alpha particle—give both its composition and its charge.
Same as a helium nucleus—2 protons and 2 neutrons, with a +2 charge
2) What happens to the atomic number when an alpha particle is emitted from an atom? What about the
mass number?
Atomic number lowers by two and the mass lowers by four
3) What happens to the atomic number when an beta particle is emitted from an atom? What about the
mass number?
Atomic number increases by one and the mass number stays the same
4) What are the three reasons that the nucleus of an atom would be unstable?
Too many neutrons, too few neutrons, too big
5) What type of nucleus is also called an alpha particle?
A helium nucleus
6) What substance could be used to stop alpha radiation? What about beta? Gamma?
Alpha—paper, beta—wood or Al foil, gamma—3” of lead or 3’ of concrete
7) How is a beta particle formed? (What type of particle breaks down?)
The breakdown of a neutron into a proton and electron
8) If the half life of a substance was 2 years, how long would it take for only ½ of an original sample to be
present?
2 years
9) If the half life of a substance is 7 days, how long would it take to have 1/8th of the original amount?
21 days
10) If a certain element has a half life of 22 minutes, how long would it take to have ¼ of the original
amount?
44 minutes
11) What is the half life of an element that decays from 100g to 25g in 4 days?
2 days
12) What type of particle is lost when argon-40 decays to potassium-40?
 particle
13) Define beta particle. What is it made of?
A type of radiation with no mass and a negative charge, same as an electron
14) What is a transuranium element?
A man-made (non-naturally occurring) element with an atomic number greater than 92 made by
bombarding the nucleus of Uranium with  particles and/or neutrons.
15) What is gamma radiation? What is its charge and mass?
High energy radiation given off with a or b radiation with no mass and no charge.
16) What is fission?
The splitting of an atom into two smaller, smiliarly sized atoms due to nuclear instability
17) What is fusion?
The combining of two small nuclei to form one larger nucleus
18) Who discovered radioactivity?
Antoine Henri Becquerel
19) How many neutrons are in lead-204?
204-82=122 neutrons
20) How many protons are in gold-197?
79 (same as atomic #)
21) What is gamma radiation made out of?
High energy EMR (electromagnetic radiation)
22) How does the atomic number and mass number of an isotope change when emitting gamma radiation?
No change
23) What is a positron?
An electron with a positive charge
24) What is a Geiger counter?
A device used to detect  radiation using the fact that it is ionizing
25) What is neutron absorption and how does it work?
The removing of neutrons (usually in from a nuclear reaction, which slows down the reaction
26) What is neutron moderation and how does it work?
The slowing down of neutrons (usually with C or H2O) in order to speed up a nuclear reaction,
because the slower neutrons have a greater chance of sticking in the nucleus and making the
fissionable material unstable
27) What type of radiation has the highest amount of energy?
gamma
28) Give all the types of radiation that have a positive charge.
Positrons and alpha particles
29) How does an element usually decay if it is bigger than element number 82?
Via alpha radiation
30) If an element had too many neutrons, how would it decay?
Via beta emission
252
248
31) Finish the following nuclear equation: 99 Es  97 Bk + ________
4
2 He
32) Finish the following nuclear equation: 5525 Mn + 11 H  2 10n + _______
54
26 Fe
15
15
1
33) Finish the following nuclear equation: 8 O + _______  7 N + 1 H
1
0n
34) Write the nuclear equation for the alpha decay of uranium-238.
238
4
234
92 U  2He + 90 Th
35) Write the nuclear equation for the alpha decay of francium-223.
223 Fr  4 He + 219At
87
2
85
36) What occurs in the nucleus during fusion?
It combines into one nuclei.
37) What is occurring in the nucleus during fission?
It splits into two similar sized pieces.
38) What is the affect of nuclear absorption in a nuclear reactor?
It makes the nuclear reaction slow down
39) What type of radiation is detected by a Geiger counter?
 radiation
40) What is the symbol for an alpha particle?
See the element in answer to #31
41) What is the symbol for a beta particle?
0 -1 e
42) What is the change in atomic number and mass number during beta emission?
Atomic number increases by one, mass number stays the same