Nuclear Chemistry
Radioactive or unstable
Nuclei that emit some form of radiation. A nucleus that does this is an unstable nucleus.
What determines the stability?
The proton : neutron ratio determines the stability.
If an atom is outside the stability band, it’s…
Unstable
There are no stable elements beyond atomic # __.
83 (everything beyond Bi is radioactive)
Another word for natural decay
Natural transmutation
Another word for natural transmutation
Natural decay
Alpha decay
Involves the emission of an alpha particle
Beta decay
Emission of a beta particle
Gamma radiation
Emission of gamma rays
Positron decay
Emission of a positron
Which type of natural decay has the greatest penetrating power?
Gamma radiation
What happens during positron decay?
Proton converts to a neutron
Half-life
The amount of time it takes for a given sample of a radioisotope to decay to 1/2 of its original mass.
Artificial transmutations
When a nucleus mutates after being bombarded with a high energy particle.
Fission
The splitting of a large nucleus (U-233, U-235, Pu-239) by bombarding the nucleus with a neutron. The results are fragments (?), energy (?), and multiple neutrons (chain reaction).
Fusion
Joining very light nuclei into a larger nucleus.
Why is fusion extremely difficult?
Fusion is extremely difficult because the positive nuclei repel. Therefore, lots of heat
and pressure is needed.
and pressure is needed.
Uses of nuclear science- energy
-nuclear reactors use fission to produce electricity
-bombs
-bombs
Uses of nuclear science- medicine
60^Co -used for radiation therapy for cancer
99^Tc -used to diagnose brain tumors
131^I -used to diagnose thyroid disorders
99^Tc -used to diagnose brain tumors
131^I -used to diagnose thyroid disorders
Uses of nuclear science- tracers
Used to follow chemical pathways
Uses of nuclear science- example of tracer
14^C in photosynthesis
Uses of nuclear science- dating
14^C : 12^C -used to date organic substances
238^U : 206^Pb -geological dating
238^U : 206^Pb -geological dating
Uses of nuclear science- food preservation
Radiation kills eggs, spores, bacteria, etc.
Particle accelerator
Uses electromagnets to accelerate charged particles
E = mc^2
What happens to some of the mass?
What happens to some of the mass?
Mass is converted into energy
Alpha particle notation
Alpha particle symbol
Beta particle notation
Beta particle symbol
Gamma radiation notation
Positron notation
Positron symbol