nuclear chemistry. radioactive decay the last unit, we learned that all elements have different...
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Nuclear Chemistry
Radioactive Decay
The last unit, we learned that all elements have different isotopes.
Example:1H (1 proton, 0 neutrons)2H (1 proton, 1 neutron)3H (1 proton, 2 neutrons)
Many isotopes are stablewill last forever
Some are not stable.
Radioactive Decay
Unstable isotopes are radioactive- able to emit particles or gamma rays
Radioactive (unstable) isotopes = radioisotopes
Radioisotopes decay into more stable forms.Radioisotopes release energy by emitting radiation
during the process of radioactive decay.
Radioactive Decay
Carbon-12 and carbon-13 are stableCarbon-14 is radioactive.
6 p+ and 6 n0 6 p+ and 7 n0 6 p+ and 8 n0
What makes a radioisotope unstable?
An isotope can be unstable if:it is too heavy (more than 83 protons).its neutron(n0) to proton(p+) ratio is too high.
its n0 to p+ ratio is too low.
Band of Stability
Types of RadiationAlpha radiation
Composition: Alpha particle (helium nucleus)
Symbol: α or HeCharge: +2Mass: 4 amuPenetrating power: Low (0.05 mm body tissue)Shielding: Paper, clothing
42
Alpha Decay
U23892
Th23490
He42
Nuclear equation:
U23892 He4
2+ Th234
90
Types of RadiationBeta radiation
Composition: Beta particle (electron)Symbol: β or eCharge: -1Mass: 1/1836 amuPenetrating Power: Moderate (4 mm body tissue)
Shielding: Metal foil
0-1
Beta Decay
C146
N147
e01-
C146
Nuclear equation:
e01-
+ N147
Types of RadiationGamma radiation
Composition: High-energy EM radiationSymbol: γ orCharge: 0Mass: 0Penetrating power: Very highShielding: Lead, concreteDecreases energy on nucleus
γ00
Tc9943 γ0
0 + Tc9943
RadioactivityRadioactive decay is known as natural
transmutation – the spontaneous nuclear decay of a radioisotope.
Occurs naturally – no outside influence needed
other types: artificial transmutation, fission, fusion
Hazards of Ionizing Radiation
Low level exposureRadiation danger is minimal.Cell damage, but cells recover and repairSeverely damaged cells self-destruct, limit damage
Non-lethal radiation exposure can still cause genetic mutation
If the mutation occurs in a gene that controls cell division, the cell could give rise to cancer.
Large radiation exposures can cause death much more quickly from severe tissue damage.
Uses of Radiation
Radioisotopic labelling – can be used to track the movement of a particular substance through a living organism.
Radiometric dating – used to determine the age of ancient objects.
Many uses in medicine, from imaging to cancer therapy.