What did Democritus think im the 5th century
All matter, whatever it was, was made up of identical lumps called Atomos
What did John dalton thing in 1804
He agreed with Democritus, and said that all matter is made up of tiny Spears atoms that can be broken up, and he thought each element was made up of a different type of atom
What did you do Thompson?
He discovered electrons that could be removed from atoms are Dalton’s theory wasn’t quite right. Suggested atoms whispers of positive charge with tiny negative electron stuck in them like food in a plum pudding.
How did Rutherford disprove the plum pudding model?
Fired a beam of alpha particles at thin gold foil-alpha scattering experiment
Nearly all particles went straight through the sheet-most of the atom was empty. Space
some were deflected more than expected,
some were deflected back from where they came-most mass of the atom must be concentrated at the centre in a tiny nucleus with a positive charge since it repelled positive alpha particles
What did neil bohr say
Electrons orbiting the nucleus do so I certain distance is called energy levels
What did James Chadwick prove?
Proof existence of the neutron, which explain the imbalance between the atomic mass numbers
Describe the current model of the atom
Nucleus is tiny, but make the most of the mass contains protons and neutrons. Overall positive charge. Rest of atom, mostly empty space negative electrons orbit, the nucleus
What is an isotope?
Element to the same number of protons, but different number of neutrons Unstable, isotopes tend to decay into other elements and give that radiation to try and become more stable
Alpha particles-helium nuclei
Alpha radiation is an alpha particles is omitted from the nucleus. An alpha particle is two neutrons and two protons like a helium nucleus. They don’t penetrate very find materials on a stop to quickly but can only travel a few centimetres in air and absorbed by sheet of paper, because of the size they are strongly ionising.
Beta particles-high-speed electrons
Fast moving electrons released by the nucleus beta particles have no mass and charge of - one moderately ionising penetrate moderately far into materials before colliding and have a range in the air a few metres absorbed by sheet of aluminium for every beta particles emitted a neutron in the nucleus has turned to a proton
Gamma rays, electromagnetic waves with short wavelength
Waves of electromagnetic radiation released by the nucleus penetrate find materials without being stopped, and will travel long distance through air weekly ionising because it tend to pass through rather than collide with atoms. Eventually, the hit something and do damage can be absorbed by thick sheets of lead or metres of concrete
What can be used to measure radiation?
Geiger muller tube and counter
What is radioactive decay in terms of trend
Entirely random, so you can’t predict exactly which nucleus in a sample of decay next week and find out the time it takes for the amount of radiation emitted by a source to half this is known as the half life can be used to make predictions rate at which is source decays its activity-becquerels
What is the half life?
The half life is the time taken, for the number of radioactive nuclei in an isotope to halve
Each time, a radioactive nucleus decays what happened to the activity
Decreases?
Where is background radiation?
The loan of the radiation that al around us in food, building, material, rocks, sun nuclear waste risk to humans measured im sieverts
Where is irradiation
Objects near a radioactive source of irritated by exposed to. It does not make it radioactive standing behind barriers being a different room reduces affects.
Contamination in radioactive particles, going into objects
If I wanted radioactive atoms and get Anum into an object is becoming contaminated, these might decay and release radiation, which could harm you, especially dangerous if they get inside your body gloves and tongues protective suits
Outside the body, which particles are most dangerous
Baton gamma, they can penetrate the body and get into delicate organs alpha can’t penetrate the skin
Inside the body alpha most dangerous to do all the damage in a very localised area better less damaging inside body radiation absorbed over a wide area. Gamma pass straight out of body.
Risks of radiation in human body
I know the atoms and molecules within living cells leading to tissue damage can cause cancer high doses can kill cells completely
How does radiotherapy treat cancer?
Sentai doses of ionising radiation, kill all living cells. It can treat cancer. Gamma are directed carefully and I just the right dosage to kill the cancer cells without damaging too many normal cells. Inevitably damaged onto normal cells.
What is nuclear fusion?
Two light nuclei collide at high speeds and join to create a larger heavier nucleus of a nucleus does not have as much mass as the two separate light nuclei did. Some mass is converted into energy and released fusion releases a lot of energy temperature and pressure is needed for Fizzah now, so high, that fusion reactors are really hard and expensive to build.
What is nuclear fission
Usually the nuclear test absorber neutron before I will split when atoms boots. It forms to lighter elements that are roughly the same size 2-3 neutrons also released when an atom splits if any of these neutrons are moving slow enough to be absorbed by another nucleus, they can cause more fission to occur-chain reaction
What happens to the energy released by nuclear fission
Energy not transferred to kinetic energy stores carried away by gamma rays can be used to heat water and make steam to turn turbine generators amount of energy produced by vision in a nuclear reactor is controlled by changing how quickly the chain reaction can occur. This is done using control roads which are Laura Andrews inside a nuclear reactor to absorb nutrients slow down. The chain reaction and controlled amount of energy released in control change reactions quickly lead to loss of energy being released as an explosion.
