atomic structure Flashcards
what are in atoms
postive charged protons, neutral neutrons, negative charged electrons
what is energy lever
the energy level of distance of electrons from atom
further away it is from energy level…
higher energyy
when can energy level change
absorb electromagentic radition from low energy level to high
emission of electrogmgetnci raditon from high level go back orginal.
what is a isotope
atom same number of protons but different number of neutrons
what is atomic number
number of protons equal to the number of electrons
what is the mass number
Number of protons plus neutrons
what happens when atom loose a isotope
atom turn postive ion
what was Dalton theory
atoms thought tiny and soild sphere that can’t be subdivided or broken
devlopment of atom -
- thought tiny sphere can’t be subdivided or broken - Dalton
- Plum pudding model, atom is ball of psotive charge with negative electron embedded- Thompson
- Alpha scattering experiment, nuclear mdoel replace plum pudding conclsuion of mass of atom concentraed at centre and was charged with +, - – Rutherford
- Bohr experiment and observaton, adpat nuclear model by suggest that electron orbit cuclear specific distance
- Rutherford more experiment - protons name was given
- Chadwick, show existenc of neutron in nuclear.
what is radioactive decayy
isoptope unstable nucleaus in becoming stable nucleus give radition, in random process
what is activity + unit
rate at which a source of unstable nuclei decays. becquerel,Bq
what is a count-rate
number of decays recorded each second by detector.
what detector use for count rate and activty of source
gieger-muller tube
what is alpha element like - what happes
4 HE 2, subtratcing 4 and 2
what is beta elemnt like - what happens
0 E -1, adding 1
nuclear radiation types
alpha, btea, gamma, neutron
what is alpha + sign
2 protons and 2 neutrons, same as helium nucleus
what ionising is alpha and passess through
strong, pass through single sheet paper
how long alpha in air and where from nucleus
5cm, ejected from nucleus
what hazard is alpha
highly likely absorved causes damage if pass through live cells
what is beta raditiaion and sign
high speed electron ejected from nucleus as a neutron turns into proton.
what ionsing and passess throgh beta
moderately, pass thorugh paper but stops at aluminiium
how long beta in air and from where in nculeus
15cm, ejected from nucleus
what hazard is beta
damage if absorbed in cells and can penetrate body to inner organs
what is gamma ray and sign
electromagnetic radiation from nucleus
what ionsing and passes through gamma
least ionsing, and pass through paper, aluminium and lead
how long in air is gamma and from where in nuclues
several metres in air before stop, and emitted from nucleus
the hazrad of gamma ray
pass through living cells without absorbed and cause ionisation
what are advantagge of long isotope half-life
-stable
-emit radioation slowly ( less hazardous exposure)
-remain radioactive.
what are advatage of short isoptoe half-life
-unstable
-emit radiation faster (exposure to hazardous)
-not remain radioactive for long
where does bakcground radition come from
natural sources and man made
natural sources types in background radiation
- radioactive rock , ground find with granite
-cosmic ray from space, very high enrgy particles travel through space and crash into earth atmosphere
man made types of background radiatiom
-Fallout from nuclear weapon testing, release radioactive isotope into environment for decades.
-Nuclear accident, radioactive isotope realse by accident at nuclear power station
what is irradiation
exposure an object to nuclear radiation
danger of irradiation to human
damage cells, DNA, cause cancer
example of irradiation
sterelization to kill bacteria, medical equipement sterlised by heating.
irridation method to object for sterlise syringe
- place inside sealed plastic wrapper to stop bacteria enter after sterliling
- place object near radioactive isotope that emit gamma radiaition to irrdate objects
what is radioactive contamination
unwanted presnese of materials containing radioactive atoms on other material
what is contamination
occur when object is exposured to source of radiation outside the object
hazard of radioative ccontamination
- decay of contaminating atoms
-burns
-cancer risk - contaminate soil
what is nuclear radiation used for in medicine
-exploartion of internal organs
-control or strcution of unwnated tissue
what is tracer
radioactive isotope into system
example of nuclear radition in medicine
- medical tracer exploration of internal organ, radioactive isotpe injected/ingested into body so movement can track and dectected outside.
-monitor kidney function, isotope will pass through kidney used
-look for damage/blockage intensines, detect tumour
why must tracer have short life
so not present in body for long period
what is nuclear fission
splitting of large and unstable nuclues
what happens during nuclear fission + show
split into 2 smaller nuclei and emit2/3 neutrons and gamma ray, energy released
what must be absorbed for nuclear fission, and involve
a neutron and involve chain reaction
what is chain reaction
controlled in nuclear reactor to control the energy released
what is nuclear fusion
joining 2 light nuclei to from a heavier nucleus
what happens to mass in nuclear fusion
some mass may be converted into the energy of radiation
Proton , neutron , electron relative charge
+1,0,-1
Proton , neutron , electron relative mass
1,1,1/2000
What happens in chain reaction of nuclear fission
After spliting nucleus into 2 smaller nuclei and emitting 2/3neutron, gamma Ray. Neutron emitted can then be absorbed by more uranium nuclei and trigger fission again.
half-life of radioactive isotope means
time taken for atoms of the isotopes in a sample to halve
explosion in a nuclear weapon is cause by…..
uncontrolled fission chain reaction
radioactive means
substance that give out alpha radiation
what is alpha best source use for
smoke detector cos do not travel far in air
what is beta and gamma best source use for
btea - thickness of material cos have enough energy to pentrate materials.
gamma - tracer / sterilise food cos longer halflife and least iosning
what happens for short half life
when decay rapidly causng great hazard - high radiation level
what happens for long half life
when decay slowly causing less hazard - low radiation level
