Atom
nucleus at the center
– positively charged protons + neutrons = nucleons
* negatively charged electrons
* Isotopes: atoms of the same element that have
the same number of protons but a different
number of neutrons
– e.g. Isotopes of Carbon
Mass number = Number of protons + neutrons
Atomic number = Number of protons and electtrons
Radioactive deacy
- Process by which the nucleus of an unstable atom loses energy by emitting radiation
– An isotope that spontaneously emits such radiation is considered radioactive
Types of decay
Radiation emitted: Alpha particle decay ( top substrict is 4, bottum must be 2)
Beta decay= 0 top subsrcipt, -1 on bottum
Gamma ray= 0 on top and bottum, 0 mass anc no charge
Radiation size
Alpha rays are the largest ( stopped by paper)
Gamma rays are fastests ( stopped concrete and lead)
Beta rays are smallest type ( stopped via layers of clothing, alimumim)
Halflife
amount of time needed for
radioactive nuclei to decrease to one half the original amount.
Exponet. decay: Formula for exponential decay:
Q=Q0(0.5)t / T
Q = new quantity, Q0 = initial quantity, t = time elapsed,
T = half-life period
t= time passed
Dangers of radiation
Penetrating power of particles and rays: ability of particles/rays to pass through air and other material is inversely related to their masses
–> Gamma rays dangerous ( require concrete and lead)
–> Alpha only paper , beta need clothing/aluminum
Shorter vs longer half life’s
Short half life: quicker decay of radioactive material, dangers are immediate ( short time, high dose)
Long half life: slow decay overtime, exposed to radiation in low dosages for prolonged period–> increases risk, can acccumnulate ( more individuals exposed)
Sources of radiation
- Natural amounts ( radon gas in homes)
- Medical diagnostic / threpautic ( cancer)
- CT/x ray machines, PET scanner ( drug to see inside)
Radiometric dating
- used in esitmating age of rocks, object based on fixed decay of radioactive isotope
Formula:
Q= Q0 (0.5) time/T half life
Energy consumed
- Global primary energy increases, mostly use of fossil fuels, natural gas, oils
- Growth of renweable and nuclear energy cause decrease in using natural energy
Energy sources
- Fossil fuels
- Nuclear energy
- Renewables
Fossil fuels
- Formed due to decay of matter of plant/animal
- Non renewable, finite reasources, hydrocarbons, emit greenhouse gase, burned co2
- Coal/gas/coal are hydorcarbons, emit greenchouse gas when burned. They trap heat, increased levels can raise the core above normal temperatures
- Hydrocarbon combusion reactions ( more co2 level) global warming
- Fossl fuels linked to heavy co2 emissions, removal of excess co2
-Normally greenhouse gases ( trap heat to warm), increase levels can be dangerous–> combustion of fossil fule increase co2 in atompshere–> main cause
Types of hydrocarbons
Coal ( organic rock, yields water, co2, energy (heat) burning combustive reactions - process of burning coal ( combusion) electricty comes from getting mechnical heat energy to electricty via generator.
Natural gas ( trapped in coal seams- release water pressure, –> methane- cleanest burning, largest part of gas
Oils ( sand,water, bitumen that is refined)
Nuclear energy
Use of nuclear energy–> energy contained within core of atom ( energy released by reaction) fission or fusion.
Fission ( splitting heavy unstable atom into lighter nuceli release energy)
Fusion ( 2 nuecli form together form heavy nucelus and release energy: sun energy produced via fusion
Nucelar fusion
- E.g. Sun’s energy is produced by nuclear fusion
– Hydrogen nuclei are converted to Helium
(chain reaction) - Why nuclear fusion is still not used to produce power?
– progress is slow due to challenges with understanding
how to control the reaction in a contained space
– expensive to create the needed conditions for a
fusion reaction
– Research continues: small fusion reactors are being
tested
Nuclear power
- neutron induced fission ( split into small nuceli+ energy)
- chain reactions, very unstable source –> chain reaction ( unstable isotopes)
- Fission controled via neurtrons absobring elements , control rods to control free neutorns.
- Neutrons can better absorb elements
We use nucelar reactions to generate nuclear energy , chemical reactions such as combustion to generate fossil energy.
–> fission reactions generate heat –> steam to power turubines–> electricity. - Fission ( heat is produced) turns water–> steam to generate turbine energy)
- Produce less co2, powerfuly and efficent , readily avaliable ( benefits)
Renewable energy
- energy obtained from natural resources, can be replinshed, source is sustainable. ( solar, wind, bioenergy) throughout lifespan.
Carbon emissions
- The overall cleanest burning fossil fuel being natural gas
Future of fossil fuels: although fossil fuels are invaluable–> large amount of co2 produced
—> new developments allow cleaner uses of fossil fuels , reducing climate impact ( carbon capture)
Benefits to nuclear energy
– lower pollution, readily free, powerful and efficent.
Nuclear capacity reached, several have operating reactors
Statistics
method of collecting, analyzing, information
Descriptive methodlogy: collect, organize, summarize data via plots
Inferferntial: making generlizations and draw conflusions from collected data
Population
Set that contains all people/objects whose properties are to be described by collector
- Sample ( subset of pop)
Representative sample ( sample exhbits characteritsics typical of those possesed by target population)
Biases
–> Different sampling methods used to seletect representaive ( standard sample to minimmze)
Selection biases: bias introduced by selection of group, data, in way that random selection does not happen, researcher selects certain people to get outcome
Participation bias: possible when individuals volunteer to particpate in study
Simple random sampling
Sample obtained in way that every element in population has equal chance for selection
Systematic sample
- Sample chosen by using simiple system, every 10th person gets sampled
