P5 Flashcards
What is the order of the development of the atom?
- 1804 John dalton-tiny spheres
- 1897 J.J Thompson- discovered electrons and the removal from atoms
- 1909 Ernest Rutherford- alpha particles charged at gold foil
- 1913 Niels bohr-electrons orbit the outershell
What are isotopes?
Atoms that have the same number of protons as each other but have a different number of neutrons
What are the different types of decay?
- Alpha-2 neutrons 2 protons, RAM- 4, charge 2+
- Beta no mass charge -1
- Gamma- no mass no charge
Alpha decay
- They are blocked by paper
- when emmitting an alpha particle the mass decreases by 4 and it loses two protons and neutrons
- Charge decreases by two because 2 protons lost
Beta decay
- Blocked by aluminium
- mass doesnt change as it has lost a neutron but gained a proton
- the charge increases by 1 because it has an extra proton
Gamma decay
- Blocked by thick led
- mass doesnt change
- charge stays the same
What is radioactive decay?
A random process in which an unstable atomic nucleus loses energy by radiation
What is a half life?
The half life is the average time taken for a sources activity to halve
Measured in Bq
What is fission?
- The splitting of big atomic nuclei
- If a large unstable nucleus absorbs a slow moving neutron, it splits into two smaller nuclei of the same size
- When uranium nucleus splits up it spits out 2 or 3 neutrons, some of which are absorbed by other nuclei causing a chain reaction
What is nuclear fusion?
- When two nuclei join to create a larger nucleus if thyre brought close to each other
- Releases a lot of energy
What is contamination?
When radioactive atoms get onto other matierials
What is irridation?
When an object/ person is exposed to nuclear radiation.
What is PET scanning?
Positron Emission Tomography is a medical imaging technique that uses radioactive isotops to visualise organ functions and diagnose medical functions
