Radioactivity Flashcards
What is a radioactive substance?
a substance containing unstable nuclei that become stable by emitting nuclei
What types of radiation can be given out by a radioactive substance? (list in order of penetration)
- Alpha radiation
- Beta radiation
- Gamma radiation
Who discovered radiation?
Marie Curie
How penetrating is alpha radiation?
- stopped by paper
- has a travel distance of a few centre meters in air
- two protons and two neutrons
we say a nucleus decays when it does what?
emits radiation
radioactive decay is
random, we can’t influence it or predict when it will happen.
where is background radiation from?
- radioactive substances in space or the environment
- devices like x-rays
How was the model of the nucleus formed?
Rutherford used measurements from alpha scattering experiments to prove that there was small positively charged mass in the centre of the atom
What could the plumb pudding explain?
why some alpha particles scattered at large angles
what is an isotope?
elements with the same number of protons but different numbers of neutrons
list two changes in the nucleus for Alpha particles decay
Nucleus losses:
- 2 protons
- 2 Neutrons
list changes in the nucleus for Beta particles
A neutron changes into a proton
list the properties of beta radiation
- stopped by thin metal
- a range of 1 meter in air
- fast moving electrons emitted from nucleus
a magnetic field can be used to do what?
separate a beam of alpha, beta and gamma radiation
list the properties of gamma radiation
- stopped by thick lead
- has an infinite range in air
- consists of electromagnetic radiation
what can ionisation cause?
killing or damaging a living cell
what does the term half life mean?
the average time it takes of a radioactive isotope to half it’s nuclei (hence the half)
the activity of a radioactive source is known as what?
the number of nuclei that decay per second
how do we choose a radioactive isotype for its job?
we take into account:
- it’s half life
- the type of radiation it gives out
radio active tracers should be what?
- beta or gamma
- last long enough to be monitored
