Atoms

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Physics (P2) Mind Map on Atoms, created by vina_56 on 16/09/2013.
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Mind Map by vina_56, updated more than 1 year ago More Less
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Created by vina_56 about 11 years ago
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Copied by vina_56 about 11 years ago
vina_56
Copied by vina_56 about 11 years ago
vina_56
Copied by vina_56 about 11 years ago
vina_56
Copied by vina_56 about 11 years ago
vina_56
Copied by vina_56 about 11 years ago
vina_56
Copied by vina_56 about 11 years ago
vina_56
Copied by vina_56 about 11 years ago
vina_56
Copied by vina_56 about 11 years ago
vina_56
Copied by vina_56 about 11 years ago
vina_56
Copied by vina_56 about 11 years ago
vina_56
Copied by vina_56 about 11 years ago
vina_56
Copied by vina_56 about 11 years ago
vina_56
Copied by vina_56 about 11 years ago
vina_56
Copied by vina_56 about 11 years ago
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Resource summary

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

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