3.4 Nuclear Chemistry Flashcards
What is a radioisotope?
An isotope whose nuclei break down spontaneously, emitting radioactive particles or rays
What is radioactive decay?
The rearrangement of an unstable nucleus into a more stable nucleus by a release of energy in the form of alpha, beta, or gamma radiation
What are alpha particles (α)?
- They consist of two protons and two neutrons
- They have a double positive charge
- They have a range of only a few centimetres in air
- They are stopped by a piece of paper
- They will be attracted towards a negatively charged plate
- They are helium ions
- They have a mass number of 4 and an atomic number of 2
What are beta particles (β)?
- They are electrons ejected from the nucleus of an atom
- They are formed by a neutron splitting into a proton and an electron
- They are able to travel over a metre in air
- They can be stopped by a thin sheet of aluminium
- They will be attracted towards a positively charged plate
- They have a mass number of 0 and an atomic number of -1
- They have a charge of -1
What are gamma rays (γ)?
- They are electromagnetic waves emitted from within the nucleus of an atom
- They can travel very far in air
- They can only be stopped by materials such as lead or concrete.
- They are not deflected by an electric field
What happens to the atomic and mass numbers of an element emitting an alpha particle?
The mass number decreases by 4
The atomic number decreases by 2
What happens to the atomic and mass numbers of an element emitting a beta particle?
The mass number stays the same
The atomic number increases by 1
What happens to the atomic and mass numbers of an element emitting a gamma ray?
Nothing, as a gamma ray is part of the electromagnetic spectrum and has no charge or mass
What is half life?
The time it takes for the radioactivity of an isotope to half
