P4e-what is radioactivity? Flashcards
What is the radioacrivity or activity of an object measured by?
The number of nuclear decays emitted per second
What does nuclear radiation do?
Ionises materials
What do radioactive substances do overtime?
Decay naturally and give out nuclear radiation in the form of alpha beta and gamma
What is a half life?
The time taken for half of the radioactive nuclei now present to decay
What is ionisation?
Particles gaining or losing electrons
Why are alpha particles good ionisers?
- relatively large, so its easy for them to collide with atoms or molecules
- highly charged, so they can easily remove electrons from the atoms they pass or collide with
Where does radioactivity come from?
from the nucleus of an atom that is unstable
What kind of nucleus is an alpha particle?
A helium nucleus
What is a beta particle?
A fast moving electron
What happens to a nucleus when an alpha particle is emitted?
- mass number decreases by 4
- nucleus has two fewer neutrons
- nucleus has two fewer protons
- atomic number decreases by 2
- new element formed
What happens to a nucleus when a beta particle is emittes?
- mass number unchanged
- nucleus has one less neutron
- nucleus has one more proton
- atomic number increases by 1
- new element formed
