211797
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Mind Map by vina_56, updated more than 1 year ago
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Atoms
- Life Cycle of Stars
- clouds of DUST & GAS - gravity makes gas/dust spiral together = protostar
- gravitational energy converted to heat energy = temp. rises
- when temp.'s high enough, hydrogen nuclei - nuclear fusion = helium nuclei = heat & light
- long stable period - heat created = outward pressure to balance gravity pulling inwards -
millions of years - massive amounts of hydrogen = MAIN SEQUENCE STARS
- eventually hydrogen = runs out - stars swells = RED GIANT (small star) - RED SUPER GIANT (big star)
- small-medium star (like Sun) - becomes unstable & ejects outer layer of dust & gas as PLANETARY NEBULA
- hot dense solid core = WHITE DWARF - cools down = BLACK DWARF - disappears
- hot dense solid core = WHITE DWARF - cools down = BLACK DWARF - disappears
- big stars - glows brightly again - fusion & expand/contract several times = heavy elements like iron in nuclear
reactions - explode in SUPERNOVA (=elements heavier than iron) - ejects to form new planets & stars
- exploding supernova - throws outer layer of dust & gas - very dense core - NEUTRON STAR - star = big enough = BLACK HOLE
- exploding supernova - throws outer layer of dust & gas - very dense core - NEUTRON STAR - star = big enough = BLACK HOLE
- small-medium star (like Sun) - becomes unstable & ejects outer layer of dust & gas as PLANETARY NEBULA
- eventually hydrogen = runs out - stars swells = RED GIANT (small star) - RED SUPER GIANT (big star)
- long stable period - heat created = outward pressure to balance gravity pulling inwards -
millions of years - massive amounts of hydrogen = MAIN SEQUENCE STARS
- gravitational energy converted to heat energy = temp. rises
- when temp.'s high enough, hydrogen nuclei - nuclear fusion = helium nuclei = heat & light
- clouds of DUST & GAS - gravity makes gas/dust spiral together = protostar
- HALF-LIFE = AVERAGE TIME it takes for the NUMBER
OF NUCLEI in RADIOACTIVE ISOTOPE SAMPLE to HALVE
- time it takes for count rate to halve
- time it takes for count rate to halve
- Nuclear Fission & Fusion
- Nuclear Fission - Splitting Up - big nuclei
- nuclear power station - nuclear reactors - uranium-235/plutonium-239
- chain reaction = nuclei split up & release heat energy - heats water - steam turbine - generator
- chain reaction = nuclei split up & release heat energy - heats water - steam turbine - generator
- nuclear power station - nuclear reactors - uranium-235/plutonium-239
- Chain Reactions
- slow moving neutron - absorbed by nucleus - unstable nucleus = split
- uranium/plutonium splits up - two/tree neutrons released = hit another nucleus = split = chain reaction
- two new smaller nuclei = radioactive - "wrong" no. of neutrons
- splitting (fission) = lots of energy
- splitting (fission) = lots of energy
- two new smaller nuclei = radioactive - "wrong" no. of neutrons
- uranium/plutonium splits up - two/tree neutrons released = hit another nucleus = split = chain reaction
- slow moving neutron - absorbed by nucleus - unstable nucleus = split
- Nuclear Fusion - Joining - small nuclei
- light nuclei (e.g. hydrogen) - join
- releases lots of energy (- more than fission)
- releases lots of energy (- more than fission)
- energy from stars - from fusion
- less radioactive waste - plenty of hydrogen as fuel
- big problem = high temp. - 10 million°C
- need strong magnetic field - to hold hydrogen at high temps/pressure
- need strong magnetic field - to hold hydrogen at high temps/pressure
- light nuclei (e.g. hydrogen) - join
- Nuclear Fission - Splitting Up - big nuclei
- Ionising Radiation
- radioactive isotopes - decay into other elements & give out radiation
- Radioactive = Random
- radioactive substances - give out radiation from nuclei - no matter what's done to them
- can't say when any one of them will decay & can't make decay happen
- unaffected by physical conditions - temp. & chemical bonding
- unaffected by physical conditions - temp. & chemical bonding
- spit out - alpha/beta/gamma
- radioactive substances - give out radiation from nuclei - no matter what's done to them
- Background Radiation - present always
- 1. unstable isotopes - all around us - air, food, building materials & rocks
- 2. space - cosmic rays - the Sun
- 3. man-made sources - nuclear accidents / dumped nuclear waste
- 1. unstable isotopes - all around us - air, food, building materials & rocks
- Alpha Particle = helium nucleus - big/heavy/slow moving
- don't penetrate far - stopped quickly - even in air
- strongly ionising - bash into & knock electrons off
- don't penetrate far - stopped quickly - even in air
- Beta Particle = Electrons - quite fast
- penetrate moderately - long range in air - moderately ionising
- for each b-particle - neutron → proton
- penetrate moderately - long range in air - moderately ionising
- Gamma Rays = Short EM Waves
- penetrate far into materials - straight through air
- weakly ionising - only pass through (don't bash)
- penetrate far into materials - straight through air
- Radiation Damage Depends on Radiation Dose = higher risk of cancer
- underground rocks - can release radioactive
radon gas - gets trapped in houses
- nuclear industry & uranium miners - 10 times
- protective clothing/face masks - no
touch/inhale - monitor with regular check-ups
- radiographers - lead aprons - stand behind
lead screens - no prolonged exposure
- high altitudes (- jet planes) - cosmic rays - pilots risk
- underground rocks - can release radioactive
radon gas - gets trapped in houses
- Alpha&Beta - Deflected by Electric & Magnetic Fields
- alpha = larger charge & feel greater force
- deflected less - greater mass
- alpha = larger charge & feel greater force
- deflected less - greater mass
- radioactive isotopes - decay into other elements & give out radiation
- Atomic Structure
- J J Thompson - "plum pudding" - atoms = spheres of positive charge with electrons stuck in them
- Rutherford & Marsden - fired alpha particles at thin gold foil - positively charged alpha would slightly deflect
- most went straight through but few bounced back = shocking
- most atom mass = centre in nucleus
most atom = empty space
- most atom mass = centre in nucleus
most atom = empty space
- Rutherford & Marsden - fired alpha particles at thin gold foil - positively charged alpha would slightly deflect
- Nuclear Model
- radius of nucleus = 10 000 times smaller than atom radius
- radius of nucleus = 10 000 times smaller than atom radius
- J J Thompson - "plum pudding" - atoms = spheres of positive charge with electrons stuck in them
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