what subatomic particles are atoms made of 

it has the same number of protons and electrons 

1/100000th of the radius of the atom - this means the vast majority of the atom is empty space 

protons + neutrons are bound together in the nucleus 

the electrons are at different distances from the nucleus. if they absorb radiation, they go to a. higher energy level away from the nucleus: when the emit it, they go to a lower energy level closer to it 

any discrete value from a set of values of a total energy for a subatomic particle confined by a force to limited space 

when atoms of an element have a different number of nuetrons 

the number of protons + nuetrons in an atom of an element 

element = sodium (Na)                                                                                                                     protons = 11 (because this is the atomic number)                                                                    neutrons = 12 (because the mass number is 23 so it has 23 protons+nuetrons, 11 are protons so the other 12 must be nuetrons)

in this example what is the element, how many protons does it have + how many nuetrons does it have

α (alpha) particles, β (beta) particles, γ (gamma) ray

what is the ionising power of alpha particles 

what is the ionising power of beta particles 

what’s the ionising power of gamma rays 

having the ability to knock electrons out of an atom 

ionized atoms can be very reactive and can react with and damage biological molecules 

they are stopped by the outermost layer of the skin 

why are alpha particles not very damaging outside the body 

if an alpha-emitter is inhaled or ingested this is very dangerous as alpha particles are the most ionising radiation 

why would it be ver dangerous if alpha particles are inhaled or ingested 

gamma-emitters as they can pass into the body but if they are inhaled/ingested they aren’t as damaging as alpha-emitters as they are the least ionising 

what are the most dangerous radiation type outside of the body 

how can alpha particles be shown in nuclear equations 

how can beta particles be shown in a nuclear equation

after the decay the nucleus has two fewer protons and two fewer nuetrons 

an electron s emitted from the a neutron in the nucleus - because the neutron has emitted some negative charge, to keep the overall charge constant it has to become a proton. therefore the nucleus after the decay has the same mass but more charge 

the time that it takes for half af the nuclei in a sample to decay to half

example of half-life: after three half-lives, how much nuclei in a sample will remain  

they are highly active (emit lots of radiation each second)

why might isotopes with ver short half-lives be dangerous 

as they remain radioactive for a very long time and so should be securely stored 

why might isotopes with long half-lives be dangerous 

example of half-lives: after 2 half-lives, how much of nuclei in a sample will remain 

radioactive decay is random - this means you never know when a particular nucleus will decay 

rocks (such as granite) and cosmic rays from space 

human are always exposed to background radiation which is from both natural + human-made sources. give examples of natural sources

weapons testing fallout, radiation from nuclear power plants 

human are always exposed to background radiation which is from both natural + human-made sources. give examples of human-made sources

- people who live in Cornwall due to the rocks there                                                                             - airline pilots get more cosmic radiation 

give examples of people who have a higher dose of background radiation 

the unwanted presence of materials containing radioactive atoms on other materials. the contaminated material decays and so the contaminated object (+ other objects nearby) receive a radiation dose 

when an object is exposed to nuclear radiation 

medical tracers are injected into the body + pass around it. a detector outside the body can tell us where the radioisotope is + then can be used in diagnosis 

how is nuclear radiation used in medicine 

- the splitting of a large nucleus into smaller nuclei.                                                                               - the large nucleus absorbs a slow neutron and then becomes unstable.                                            - it then split into two smaller nuclei + also emits two or three nuetrons + gamma rays 

energy is released in the form of the gamma rays and the kinetic energy of the products 

a chain reaction may occur if one of the nuetrons is then absorbed by another nucleus and causes another fission event 

when may a chain reaction occur in nuclear fission

how are chain reactions controlled in nuclear power plants 

two small nuclei fuse to form a heavier nucleus. some mass is lost + this is converted to energy, released as radiation 

does nuclear fission of fusion release more energy per kg of fuel

the positive nuclei will repel each other so it most be going very fast to collide 

why can nuclear fusion only take place at high temperatures + pressures 

so they can pass out of the body and also they are the least ionising 

gamma emitters are also used to emit a focused beam of gamma rays onto cancerous areas - because gamma rays kill living tissue, the cancerous cells are destroyed.

what is another use of gamma emmiters for helping fight cancer 

scientists knew that atoms contained negative electrons but were overall uncharged so they knew there must be some positive model in the atom - negativly charged electrons were embedded into a spherical area of positive matter

- he devised an experiment to investigate the atom where alpha particles were fired at thin gold foil                                                                                                                                                - it was expected that the alpha particles would pass right through - most did but some were deflected and a very few bounced right back - the findings weren’t consistent with the plum pudding model so he proposed the nuclear model

describe Rutherford’s gold foil experiment 

a small ensemble nucleus is the middle and electrons orbiting outside. Chadwick discovered nuetrons + the model of the atom was changed again to include protons + nuetrons in the nucleus 

-most of the alpha particles passed straight through so the atom must mostly be empty space -some of the alpha particles were deflected away so there must be an area of positive charge -some of the particles bounced back so there must be a very small, very dense area in the atom

what three pieces of evidence were used to work out Rutherford’s new model

certain isotopes has too many nuetrons or ot enough so they become unstable. the nucleus changes to become more stabl + emits some radiation (this is radioactive decay)

its activity which is measured in becquerel (Bq) where 1 Bq is one deca per second 

what is the rate at which a nucleus decays called

the positively charged central core of an atom consisting of protons + neutrons and containing all its mass

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Free AQA GCSE Physics Topic 4: Atomic Structure Flashcards, Notes & More!

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[Seperate] Physics Topic 8: Space & other (MASTER Booklet)

Forces - GCSE physics