P6.1

Created by

khadijah<3

Cards (23)

what are the set distances that electrons in an atom orbit around the nucleus called?
energy levels
how do electrons move between energy levels?
by absorbing or emitting electromagnetic radiation
what happens when electrons absorb EM radiation?
they move to a higher energy level
what happens when an electron moves back down to its original energy level?
it will emit a wave of EM radiation
what are the 3 types of radiation that can be emitted?
alpha, beta and gamma
what is an alpha particle the same as?
helium nucleus
what does an alpha particle consist of?
2 neutrons and 2 protons
what happens when an alpha particle is lost?
mass number decreases by 4
atomic number decreases by 2
what are beta particles?
fast-moving electrons
how are beta particles produced?
when a neutron changes into a proton and an electron
what is emitted in beta decay?
electron
what remains in nucleus in beta decay?
proton
why does the mass number stay the same in beta decay?
because the electron that is emitted has a negligible mass compared to neutrons and protons
what happens in gamma decay?
a gamma ray is emitted from an unstable nucleus
what happens to the nucleus in gammad decay?
the nucleus is less energetic but the structure does not change
it doesnt affect the mass number or atomic number but reduces the energy of the nucleus
what can alpha be stopped by>?
paper
what can beta be stopped by?
a few mm of aluminium
what can gamma be stopped by? 
a few mm of lead
which has the highest ionising power?
alpha
which has the highest penetrating power?
gamma
it is impossible to know when a particular unstable nucleus will decay but the rate at which the activity of a sample decreases can be known. what is this known as?
the half life
what is half life defined as?
the time it takes for the number of nuclei of a sample of radioactive isotopes to decrease by half
what does the amount decrease by each half life?
half