Radioactivity Principles Flashcards
What is radioactivity?
The process by which unstable atomic nuclei release energy in the form radiation to become stable
Name 3 primary types of radioactive decay
Alpha, beta, and gamma
What particle is emitted during alpha decay?
An alpha particle→ consisting of 2 protons and 2 neutrons → is a helium nucleus
What happens during beta decay?
A neutron is converted into a proton and an electron, with the electron (beta particle) being emitted
What is gamma decay?
The emission of high - energy electromagnetic radiation from an excited nucleus as it returns to a lower energy state
Define half-life
Time required for half the atoms in a radioactive sample to decay
Who discovered radioactivity?
Henri becquerel → significant contributions from Marie and Pierre curie in 1896
What are isotopes
Atoms of the same element with the same number of protons but different numbers of neutrons
What is a radionuclide?
A radioactive isotope of an element
How is radioactivity measured?
Using units → becquerel ( Bq) or curie ( ci)
What is the biological effect of radiation called?
Radiation dose → measured in sieverts ( sv)
What is the principle of radioactive decay law?
The rate of decay is proportional to the number of undecayed nuclei present
What type of radiation has the highest penetration power?
Gamma radiation
If a radioactive substance has a half life of 5 years,how much of a 10g sample remains after 15 years?
1.25g
True or false → Alpha particles can travel through several centimeters of lead
False
True or false → The curies discovered the elements polonium and radium
True
Explain the difference between ionising and non-ionising radiation?
Ionising radiation has enough energy to remove tightly bound electrons from atoms, creating ions. Examples include alpha,beta and gamma particles. Non -ionising radiation lacks the energy to ionise atoms. Examples include microwaves,visible light and radio waves
Calculate the activity of a radionuclide with 500 decays per second in Bq.
Bq = one decay per sec
500 decays = 500Bq
A sample of carbon -14 has a half life of 5730 years. If a fossil contains 25% of its original carbon-14, how dd is the fossil?
25% of original carbon-14 remains → meaning 2 half lives have passed.
2 half lives x 5730 =11460 years
