atomic structure

Question 1

whats the plum pudding model

Answer 1

the plum pudding model showed the atom as a ball of positive charge with electrons stuck in it

Question 2

whats the alpha scattering experiment

Answer 2

rutherfored fired alpha particles (ox) at a sheet of thin gold foil. he deduced the following most of the alpha particles go through undeflectd this shows that most of the atom is empty space. some deflected by small angles which tells us the atom has a nucleus with a positive charge
some are deflected by large angles. this shows most of the atoms mass is concentrated in nucleus

Question 3

mass and charge of proton neutron and electron

Answer 3

proton 1 +1
neutron 1 0
electron 1/2000 -1

Question 4

whats the mass number

Answer 4

number of protons plus neutrons

Question 5

whats the atomic number

Answer 5

the number of protons in the nucleus

Question 6

atoms of an element always have the same..

Answer 6

atomic number

Question 7

whats an ion

Answer 7

atoms are neutral but if some electrons are added or removed the atom becomes a charged particle called an ion

Question 8

what do the ions still have the same as with the atom

Answer 8

the ions still have the same number of protons and neutrons as usual, but a different number of electrons

Question 9

whats it called if an atom has had electrons added or removed

Answer 9

ionisation

Question 10

whats an isotope

Answer 10

different forms of the same element which have the same number of protons but a diff number of neutrons this means they have the same atomic no. but a different mass no.

Question 11

what are unstable isotopes and what does it mean

Answer 11

the unstable isotopes are radioactive ,which means they decay into another elements and give out radiation

Question 12

whats radioactive decay

Answer 12

some atomic nuclei are unstable in order for them to become more stable they emit ionising radiation. the process of radioactive decay is random and unpredictable. there r 3 types

Question 13

whats the 3 types of decay

Answer 13

alpha,beta and gamma

Question 14

whats alpha decay

Answer 14

an alpha particle (helium nucleus) is emitted from the nucleus. an alpha particle is 2 protons and 2 neutrons. during alpha decay mass no. decreases by 4 , atomic no. by 2 and charge by 2

Question 15

whats beta decay

Answer 15

when a neutron turns into a proton and an electron. electron leaves the nucleus. after beta decay mass number is unchanged atomic no increases by 1 charge has increased by 1

Question 16

whats gamma decay

Answer 16

after a nucleus has undergone alpha or beta decau the excess energy in the nucleus is released as a gamma wave. after gamma decays the nucleus has not changed

Question 17

whats gamma

Answer 17

its a high energy electromagnetic wave

Question 18

whats activity measured in

Answer 18

becquerels (Bq) 1 Bq - 1 decay per second

Question 19

whats activity

Answer 19

rate of which a sample decays

Question 20

half life definition

Answer 20

average time taken for count rate to halve

Question 21

whats the count rate

Answer 21

when were measuring the radiation emitted from the source we use a GM tube to detect the radiation. the amount detected per second is known as the count rate

Question 22

for alpha whats the
structure
penetrating ability
range in air
ionising power
uses

Answer 22

2 protons 2 neutrons
paper
2-3cm
most ionising
smoke detector

Question 23

for beta whats the
structure
penetrating ability
range in air
ionising power
uses

Answer 23

fast moving electron
2-3mm aluminium
1m
less ionising than alpha
monitoring thickness of aluminium foil

Question 24

for gamme whats the
structure
penetrating ability
range in air
ionising power
uses

Answer 24

electromagnetic waves
thick led/concrete
most penetrating
unlimited
less ionising
detecting leaks

Question 25

when does irradiation occur

Answer 25

occurs when exposed to radiation from a source

Question 26

how to reduce risk of irradiation

Answer 26

to reduce the risk we keep sources in lead lined boxes. we also make sure that we keep a safe distance from a source

Question 27

when does contamination occur

Answer 27

occurs when radioactive material is inhaled or ingested this also means that a person is irradiatedb

Question 28

whats effects of radiation on living cells

Answer 28

alpha,beta and gamma radiation enter living cells they collide with molecules and cause them to become ionised. this either damagaes or destroys the molecules. this might then cause cells to be killed or DNA to be damaged

Question 29

effects of low doses

Answer 29

cause minor damage without killing cells. often mutations occurs which may cause cells to divide uncontrollably, causing cancer

Question 30

effects of high doses

Answer 30

these tend to cause death of a large number of cells, which then causes radiation sickness the extent of the damage done depends upon how much exposure there is to radiation type of radiation absorbed

Question 31

what are the medical uses of radiation

Answer 31

tracers - certain isotopes r injected into the body and their progress around the body can be monitored externally by detector. this helps to diagnose medical conditions e.g. cancerous tumours radiotherapy - gamma radiation can be used to treat cancer by exposing the tumour cells to intense gamma radiation. the radiation must be targeted accurately at the tumour cells to avoid harming the healthy tissue as any damage to healthy tissue will make patient unwell

Question 32

risk v benefit of radiation in medical use

Answer 32

doctors will consider the risk of treatments vs the benefit to a patients health e.g. imaging using radiation poses a small risk but has a potentially large benefit to the survival of a patient

Question 33

whats nuclear fission

Answer 33

when an unstable uranium nucleus absorbs a free neutron and splits into 2 roughly equal sized daughter nuclei. lots of energy and 2/3 neutrons are released. the neutrons that are produced can go on t cause further fission events causing a chain reaction

Question 34

whats the only isotope that can undergo fission

Answer 34

uranium 235 and plutonium 239

Question 35

wheres the energy released during fission transferred

Answer 35

the energy released during fission is transferred to the kinetic store of the daughter nuclei and the neutrons. In a nuclear power station this energy is then transferred to thermal stores of water which turns to steam which turns a turbine + then turns a generator

Question 36

definition of fusion and where does it happen naturally

Answer 36

when 2 lighter nuclei join together to form a larger, more stable nucleus. this process releases energy and occurs naturally in stars e.g. sun releases energy