Half-Life
What are at least 2 helpful uses of Nuclear reactions?
treat cancers, generating electricity (power plants)
What is an alpha particle made of?
2 protons and 2 neutrons
What is a beta particle made of?
A beta particle is 1 emitted electron.
What part of the atom is involved in a normal chemical reaction?
Electrons
Thorium-234 has a half-life of 24 days. If you start with 100 g, how many grams are left after 48 days?
25 grams
What are three types of nuclear radiation?
alpha, beta, gamma
What is the correct way to write an alpha particle in a nuclear equation?
42 He
Which number is not changed during beta decay?
The mass number is not changed during beta decay.
What part of the atom is involved in a nuclear reaction?
The nucleus
Plutonium-239 has a half-life of 24,110 years. How much of a 100 g sample remains after 96,400 years?
6.25 grams
What is the mass of 1 gamma ray?
Gamma rays are pure energy and have no mass. Therefore, the answer is 0.
How does the mass number change during alpha decay?
The mass number decreases by 4 during alpha decay.
What happens during the process of beta decay?
A neutron transforms into 1 proton and 1 electron. The proton stays in the nucleus and the electron is emitted.
Why is the mass number of an alpha particle equal to 4?
Because an alpha particle has 2 protons and 2 neutrons. The mass number is the sum of the protons and neutrons. 2 + 2 = 4.
Radium-266 has a half life of 1599 years. If you start with 15.0 mg, how much is left after 6369 years?
0.94 mg
When looking at a nuclear equation, how can you tell whether it describes alpha decay or beta decay?
Look to see whether an alpha particle or beta particle is being emitted.
How does the atomic number change during alpha decay?
The atomic number decreases by 2.
Does beta decay change which element the atom is?
Yes. The atomic number increases by 1, which transforms the atom into a different element.
Give 1 example of harmless radiation.
[answers will vary]
Thorium-227 has a half-life of 16 days. How many days are required for three-fourths to decay?
32 days
Why can nuclear reactions change an atom from one element to another?
Because nuclear reactions can change the number of protons in the nucleus, and the number of protons determines the identity of the element.
What are the 2 products formed when the following atom goes through alpha decay:
24796Cm
24394Pu + 42He
What 2 products are formed when the following atom goes through beta decay:
3516S
3517Cl + 0-1e-
Why are radioactive isotopes unstable?
Because there is an imbalance in the number of protons and electrons within the nucleus.