Chapter 15: Radiation Flashcards
Background Radiation, Count Rate, Nuclide Notation, Radioactive Decay, Alpha Decay, Beta Decay, Gamma Ray, Neutron Emission, Properties of Radiation, Half Life, Nuclear Equations, Nuclear Fission and Fusion, Effects of Radiation on Humans
What is background radiation defined as?
The radiation that exists around us all the time
What are the two main sources of background radiation?
Natural: Radon Gas, Rocks, Cosmic Rays, Carbon-14 in Biological Material
Man-made: Medical Sources, Nuclear Waste, Nuclear Fallout and Accidents
What is the name given to the amount of radiation a person recieves?
A dose
How is ionising nuclear radiation measured?
Using a detector that is connected to a counter
What is a count rate?
The number of decays per second detected by a detector and recorded by the counter
Measured in counts/min or counts/s
How is the count rate related to the distance the detector is from the source?
Inversely related, as the radiation spreads out more the further away the counter is from the source
What is the most common device used to measure and detect radiation?
Geiger-Muller tube
What is the unit of activity?
Becquerel (Bq) or Disintergrations per second
SI Units: Becquerel (Bq)
What is the mass number of an atom?
The number of protons and neutrons in a nucleus of an atom
What is the atomic (proton) number of an atom?
The number of protons in a nucleus of an atom
What are Isotopes?
The same element with a different number of neutrons / different mass
What is radioactive decay?
When an unstable nucleus stablises itself by decaying, emitting alpha particles, beta particles, gamma rays or neutrons
When does a nucleus undergo alpha decay?
When the nucleus has too few neutrons
What does alpha decay emit?
A particle containing 2 neutrons and 2 protons, or a Helium-4 nucleus (alpha particle)
How does alpha decay affect the mass and atomic number of the nucleus?
Alpha decay causes mass number to decrease by 4, and atomic number to decrease by 2
When does a nucleus undergo beta decay?
When the nucleus has too many neutrons
What happens during beta decay?
A neutron will decay into a proton, a fast moving electron (and an anti-neutrino). The electron (or beta minus particle) is emitted
How does beta decay affect the mass and atomic number of the nucleus?
Beta decay causes atomic number to increase by 1, and mass number remains unchanged
Why does gamma radiation occur?
Even after undergoing alpha or beta decay, the nucleus will often still be too hot, and will have to emit an electromagnetic wave, called a gamma ray
What is neutron emission?
When a nucleus has too many neutrons or too few protons, the nucleus will emit one or more neutrons
How does neutron emission affect mass and atomic number of the nucleus?
Neutron emission causes mass number to decrease by one, and atomic number remains unchanged
What is alpha and beta particles, and gamma rays penetrating power?
Alpha particle: Skin / Paper
Beta particle: 3 mm aluminium foil
Gamma ray: Lead / Concrete
What is alpha and beta particles, and gamma rays ionising power?
Alpha particle: High
Beta particle: Low
Gamma ray: Very low
What is alpha and beta particles, and gamma rays range in air?
Alpha particle: Less than or equal to 5 cm
Beta particle: Around 1 m
Gamma ray: More than 1 km
What is the half-life of an atom / nucleus?
The time it takes for half of the unstable nuclei in a sample of nuclei to decay or for the count rate / activity to half
What is the difference between nucleur fusion and fission
Nucleur fission is when a nucleus splits into two smaller nucleus, nucleur fusion is when two smaller nucleus join to form a bigger nucleus
What equation connectes the small amount of the particle’s mass being converted to energy?
Energy (E) = Mass (m) x Speed of light^2 (c^2)
How does radiation negatively impact the human body?
The genetic material of the cell (DNA) can be damaged via ionisation, which can lead to cancer. Radiation can also deposit large amounts of energy into the body, which can damage and destroy cells
When can alpha, beta and gamma radiation harm the body?
Alpha radiation: When source is inside the body
Beta and Gamme radiation: When source is both inside and outside the body
What are some negative impacts of radiation on the eyes, thyroid, lungs, stomach, reproductive organs, skin and bone marrow?
Eyes: Cataracts
Thyroid: Thyroid cancer
Lungs: Damage DNA through breathing of radioactive isotopes
Stomach: Radioactive material can sit in stomach andd irradiate for a long time
Reproductive organs: Sterility or mutation
Skin: Burns or skin cancer
Bone marrow: Leukaemia and other blood diseases
How does gamma rays help detect tumours?
Tcchnitium 99 can be taken into the body which allows a gamma camera to show images of internal organs via gamma rays
How does beta particles help treat thryoid disorder?
Beta particles in Iodine 131 will destroy thyroid cells, including cancerous cells. As the isotope only has a half life of 8 days, it will not remain in the body for very long
