State the names of people who found and years every atomic structure was found
Dalton 1800 everything is made of tiny spheres that cannot divide
JJ Thomson 1897 electrons plum pudding model
Rutherford 1911 gold foil experiment positive nucleus with cloud of electrons surrounding it
Bohr 1913 electrons exist in fixed orbits
Define radioactive decay
Nucleus gives out radiation as it changes to become stable
What is decay recorded by
A detector per second
State ionising ability, penetration and what stops alpha radiation
High ionising
Low penetration
5cm of air
State ionising ability, penetration and what stops beta radiation
Medium ionising
Medium penetration
Sheet of paper
State ionising ability penetration and what stops gamma radiation
Low
High
Few cm of lead
Define half life
The amount of time half of the nuclei from the sample takes to decay
Define short half life
And long half life
Stong radioactive then dies down
Weak radioactive for a long time
Define contamination
Unwanted presence of radioactive atoms on other materials
Define irradiation
Source of radiation
Define background radiation
Weak radiation that can be detected from natural / external source
Uses of radiation
Tracers
Chemotherapy Gamma emitters used to emit gamma radiation directed onto areas of the body with cancerous cells
Define nuclear fission
Splitting of a large unstable nuclei
Define nuclear fission
Two small nuclei fuse to form a heavier nucleus
