Topic 5: Nuclear physics Flashcards
(21 cards)
What is the composition of a nucleus?
The nucleus is composed of protons and neutrons.
What are the relative charges of protons, neutrons, and electrons?
Protons: +1, Neutrons: 0, Electrons: -1.
What is the relationship between the proton number and the relative charge of a nucleus?
The proton number (atomic number) determines the relative positive charge of the nucleus.
What are the terms “proton number” (atomic number) and “nucleon number” (mass number)?
Proton number (Z) is the number of protons, and nucleon number (A) is the total number of protons and neutrons in the nucleus.
How do you calculate the number of neutrons in a nucleus?
Number of neutrons = Mass number (A) - Proton number (Z).
What is nuclide notation?
Nuclide notation is written as 𝑋 𝑍 𝐴 , where X is the element symbol, A is the nucleon number (mass number), and Z is the proton number (atomic number).
What is an isotope?
An isotope is a variant of an element that has the same number of protons but a different number of neutrons.
What are radioactive isotopes?
Radioactive isotopes are isotopes that are unstable and decay to form other elements, often emitting radiation.
What is ionising nuclear radiation?
Ionising nuclear radiation has enough energy to remove electrons from atoms, creating ions.
What is background radiation?
Background radiation is the radiation from natural and artificial sources in the environment.
What are the sources of background radiation?
Sources include radon gas, rocks and buildings, food and drink, and cosmic rays.
How is ionising radiation measured?
Ionising radiation is measured using a detector connected to a counter, and can be expressed in counts per second or counts per minute.
What are alpha (α), beta (β), and gamma (γ) emissions?
Alpha (α): Consists of 2 protons and 2 neutrons, highly ionising but weakly penetrating.
Beta (β): Consists of high-energy electrons, moderately ionising, and moderately penetrating.
Gamma (γ): Electromagnetic radiation, weakly ionising but highly penetrating.
What happens during radioactive decay?
Radioactive decay is the spontaneous change of an unstable nucleus, which may emit alpha particles, beta particles, or gamma radiation.
What happens during beta decay?
A neutron in the nucleus transforms into a proton and emits an electron (beta particle).
How is the emission of alpha, beta, and gamma radiation shown in nuclide notation?
Decay equations use nuclide notation to show changes, for example:
Alpha Decay:
ₐᶻX → ₐ₋₄ᶻ₋²Y + ⁴₂He
The original nucleus X emits an alpha particle (⁴₂He), resulting in a new nucleus Y with:
Mass number decreased by 4
Atomic number decreased by 2
Beta Decay (β⁻ decay):
ₐᶻX → ₐᶻ⁺¹Y + ⁰₋₁β
The original nucleus X emits a beta particle (⁰₋₁β), resulting in a new nucleus Y with:
Mass number unchanged
Atomic number increased by 1
What is the half-life of a radioactive isotope?
The half-life is the time taken for half of the nuclei in a sample to decay.
How do you calculate the half-life of an isotope?
Use decay tables or graphs to determine the time it takes for half of the radioactive nuclei in a sample to decay.
What are some applications of radioactivity?
Applications include:
Household fire (smoke) alarms
Irradiating food to kill bacteria
Sterilising equipment using gamma rays
Measuring and controlling material thickness
Diagnosing and treating cancer using gamma rays
What are the effects of ionising radiation on living organisms?
Ionising radiation can cause cell death, mutations, and cancer.
How should radioactive materials be safely handled?
Radioactive materials should be handled using time (minimising exposure), distance (increasing distance from source), and shielding (using appropriate materials to block radiation).
