Chapter 19Chapter 19
Nuclear ChemistryNuclear Chemistry
Marie Sklodowska Curie
Types of Nuclear Types of Nuclear ReactionsReactions
1. Radioactive Decay1. Radioactive Decay
Emission of an alpha (Emission of an alpha () particle, ) particle, beta (beta () particle, or gamma () particle, or gamma () ) radiation radiation results in slightly results in slightly lighter and more stable nucleilighter and more stable nuclei
2. Nuclear disintegration2. Nuclear disintegration
Nucleus bombarded with particles Nucleus bombarded with particles (e.g. (e.g. ,p+, n,p+, n00) ) nucleus emits p nucleus emits p++ or or nn00 and becomes more stable and becomes more stable
3. Fission3. Fission
Very heavy nucleus splits to form Very heavy nucleus splits to form medium mass nucleimedium mass nuclei
4. Nuclear Fusion4. Nuclear Fusion
Light mass nuclei combine Light mass nuclei combine form form heavier, more stable nucleiheavier, more stable nuclei
RadioactivityRadioactivity
Spontaneous disintegration of Spontaneous disintegration of unstable nuclei unstable nuclei emitted emitted
e.g. U-238, radium (Ra-226)e.g. U-238, radium (Ra-226)
Types of radiation Types of radiation
Alpha (Alpha ())
Helium nucleusHelium nucleus 22++ chg. chg. Moves at 1/10 cMoves at 1/10 c Low penetrating powerLow penetrating power
Beta (Beta ())
ElectronsElectrons 1- chg1- chg Moves at close to cMoves at close to c 100x penetrating ability of 100x penetrating ability of
Gamma (Gamma ())
Electromagnetic wavesElectromagnetic waves 0 chg0 chg Highest penetrating powerHighest penetrating power
Half LifeHalf Life
Time during which half of a given # Time during which half of a given # of atoms of a radioactive isotope of atoms of a radioactive isotope decaysdecays
Half Life exampleHalf Life example
If you start with 7.0g of radioactive If you start with 7.0g of radioactive Radon-222 (half life = 3.823 days) how Radon-222 (half life = 3.823 days) how many g remain after 11.47 days?many g remain after 11.47 days?
# half lives = time elapsed x 1 half life/ # half lives = time elapsed x 1 half life/ 3.823 days3.823 days
Original amt. of Radon-222 remaining Original amt. of Radon-222 remaining x ½ for each half life = amt. of radon-x ½ for each half life = amt. of radon-222 remain.222 remain.
(cont.)(cont.)
3 half lives = 11.47 days x 1 half life/ 3 half lives = 11.47 days x 1 half life/ 3.823 days3.823 days
7.0g x ½ x ½ x ½ = 0.88 g Radon-7.0g x ½ x ½ x ½ = 0.88 g Radon-222222
Properties of naturally Properties of naturally occuring radioactive occuring radioactive
isotopesisotopes Expose filmExpose film Produce electric chg. in surrounding Produce electric chg. in surrounding
air (Geiger counter)air (Geiger counter)
properties (cont.)properties (cont.)
Cause fluorescence when mixed with Cause fluorescence when mixed with certain cmpdscertain cmpds
Properties (cont.)Properties (cont.)
Physiological effects Physiological effects e.g. medical treatments, killing e.g. medical treatments, killing
bacteriabacteria
Properties (cont.)Properties (cont.)
DecayDecay Radioactive isotopes decay into simpler Radioactive isotopes decay into simpler
atomsatoms
Nuclear equationsNuclear equations
Transuranium elementsTransuranium elements
Elements with more than 92 protons Elements with more than 92 protons First two produced were neptunium First two produced were neptunium
and plutoniumand plutonium
ApplicationsApplications
1. Radioactive dating1. Radioactive dating
radioactive substances decay at known radioactive substances decay at known ratesrates
Rates are constantRates are constant % parent v. daughter isotopes % parent v. daughter isotopes age of age of
materialmaterial e.g. C-14 dating of ancient Egyptian e.g. C-14 dating of ancient Egyptian
lumber lumber ½ radiation of carbon in living ½ radiation of carbon in living trees, half life of carbon-14 is 5730 yrs., trees, half life of carbon-14 is 5730 yrs., therefore lumber is 5700 yrs. oldtherefore lumber is 5700 yrs. old
2. Radioisotopes in 2. Radioisotopes in medicinemedicine
3. Nuclear Power Plants3. Nuclear Power Plants
Nuclear chain reaction Nuclear chain reaction
4. Nuclear Fusion4. Nuclear Fusion
‘‘ultimate’ energy sourceultimate’ energy source Occurs in stars, e.g. the sunOccurs in stars, e.g. the sun 100,000,000 K temp 100,000,000 K temp