What is nuclear decay?
The process by which an unstable nucleus emits radiation
It involves the transformation of radioactive isotopes.
Define radioactive isotopes.
Isotopes with an unstable nucleus that decay and emit radiation
They undergo nuclear decay over time.
What are the types of nuclear decay?
- Alpha decay
- Beta decay
- Gamma decay
Each type has distinct characteristics and effects.
What is half-life?
The time taken for the number of radioactive nuclei to reduce to half of its initial value
It is a measure of the stability of a radioactive isotope.
Define decay constant.
The probability that a given nucleus will decay in one second
It is related to the half-life of the isotope.
What does activity refer to in nuclear decay?
The rate of decay of unstable nuclei
Measured in units of Bq (Becquerel).
What are the characteristics of alpha particles?
- Strongly ionizing
- Short range in air
- Stopped by paper
- Deflected by magnetic fields
Alpha decay decreases the atomic number by 2 and mass number by 4.
What are the characteristics of beta particles?
- Moderately ionizing
- Range in air about 1m
- Stopped by thin metal
- Deflected by magnetic fields (opposite direction to alpha)
Beta decay increases the atomic number by 1.
What are the characteristics of gamma rays?
- Weakly ionizing
- Obey inverse square law in air
- Stopped by 1m concrete
- Not deflected by magnetic fields
Gamma rays are high-energy electromagnetic radiation.
Fill in the blank: The rate of production of C-14 decreases over time as it undergoes _______.
nuclear decay
This affects the ratio of C-14 to C-12 in dating methods.
What is the formula for alpha decay?
292U → 230Th + 2a
This indicates the emission of alpha particles.
What is the formula for beta decay?
16C → 14N + -9B + Ve
Here, Ve represents the neutrino emitted.
What is the formula for calculating the number of radioactive nuclei remaining?
N = Noe -it
This formula accounts for the decay over time.
What does the formula A = 2N represent?
The relationship between activity and the number of radioactive nuclei
A is the activity and N is the number of nuclei.
What is background radiation?
Radioactive isotopes in the environment
Sources include rocks, air, water, and cosmic rays.
How does background radiation affect cancer rates?
May affect cancer rate and is responsible for some mutations that drive evolution
It is important to consider background radiation when studying health effects.
Before plotting an activity graph, what must be corrected for background radiation?
The count rate
Otherwise, T½ will be overestimated.
Define binding energy.
The energy needed to separate all nucleons in the nucleus
Mass defect is a key concept related to binding energy.
According to Einstein’s equation E = mc², what happens to mass when the energy of the nucleus increases?
The mass must increase
This is due to the relationship between mass and energy.
What is the most stable isotope?
Fe — 56
For A > 56, the binding energy per nucleon decreases.
What occurs during nuclear fission?
Split a large nucleus into small nuclei
This process releases energy because the binding energy per nucleon of the fragments increases.
What is produced in a nuclear fission reaction?
- More than 1 neutron
- Energy
Each neutron can induce further nuclei to fission, leading to an exponential growth of the reaction.
What is a chain reaction in nuclear fission?
A reaction where each neutron produced can induce further fission
This leads to an exponential increase in the reaction rate.
What is the relationship between binding energy and the stability of isotopes?
Higher binding energy indicates greater stability
Fe — 56 has the highest binding energy per nucleon.
