Atomic structure and Radioactivity Flashcards
John Dalton
19th century
Atoms were solid sphere
JJ Thompson
19th century
PlumPudding model
Ernest Rutherford
1909
Geiger and Marsden alpha particle scattering experiment
alpha particles most had no effect taken on them implying they were mostly empty space
some path was diverted from the gold sheet showing they were postiviley charged
some completely bounced back showing they had mass concetrated at their center
Neils Bohr
~1911
Electrons reside in shells in the atom
James Chadwick
~1940
Neutrons in the nucleus
What is an isotope
An isotope is an element with the same number of protons but a different number of neutrons. Same atomic number different mass number
What is an unstable isotope and what does it do
An isotope that cannot stay in its current atomic state
They decay and give out radiation
What is Alpha RADIATION and its emittion
Alpha particle is emitted from the nucleus of a radioactive nuclei
What is an alpha particle
A helium Nucleus
What does it mean if radiation is ionizing
It can knock electrons out of their orbit
Properties of alpha radiation
Cannot travel far in air
Stopped by skin and paper
Most ionizing
What is beta radiation and its emittion
Fast moving electron emitted from a neutron splitting into a proton and an electron
Properties of beta radiation
Travels a few cm in air
Goes through skin and paper, stopped by aluminium
Second most ionising
What is gamma radiation
When a gamma wave is emitted by nucleus getting rid of excess energy
Gamma radiation properties
Travels infinite in air
Goes through skin, paper, aluminum, stopped by lead and thick concrete
Least ionising
What is half life?
Time taken for number of radioactive nuclei to halve in a substance
What is radioactive decay measured in
Bequerels (Bq) Bequerels is number decays per second
What is irradiation
When things are placed near a radioactive source and it effects them
How to stop irradiation when handling a source
Stand behind something lead line and/or use a robot arm to operate with it
How to write an alpha particle decay equation
Radioactive nuclei goes to alpha particle plus other radioactive minus alpha particle
What is contamination
Radioactive atoms get inside the object e.g radioactive particles getting inside the body
How to stop contamination from humans
Wear protective equipment when handling radioactive nuclei
ReasonS why Alpha radiation is the most dangerous inside the body
It is the most ionizing
It cannot penetrate skin to get out the body
What happens in nuclear fission
- Large radioactive atoms split in half because they are unstable
- Huge amount of energy is released
- Neutrons are released and hit, split more atoms causing a chain reaction
- This evaporates water to steam which spins a turbine
