radioactive isotope isotope which is unstable. it emits radiation & changes into another kind of...
TRANSCRIPT
Radioactive Isotope
Isotope which is unstable. It emits radiation &
changes into another kind of atom.
Transmutation Reaction
When one kind of nucleus changes into another kind
of nucleus.
Relationship between stability and energy
As stability , energy .
Stability
Depends on neutron to proton ratio.
Which elements are unstable?
All the elements with atomic number > 83 (or
beyond Bismuth)
Types of Radiation
Alpha, Beta, GammaSeparated by electric or
magnetic fields.
Least penetration power
Alpha radiation. Shielding can be paper or cloth.
Most penetration power
Gamma radiation. Requires lead/concrete
shielding.
2He or 2
Symbol for alpha radiation
4 4
2He or 2
Same as the nucleus of a helium atom
4 4
2He or 2
Mass = 4 amuCharge = +2
4 4
-1e or -1 or - or
Symbol for beta particle
0 0
-1e or -1 or - or
Fast moving electron originating from nucleus
0 0
-1e or -1 or - or
Mass = “zero”Charge = -1
0 0
+1e or +1 or +
Symbol for positron.
0 0
+1e or +1 or +
Mass = “zero.”Charge = +1.
Positive electron
0 0
0 or
Symbol for gamma radiation.
0
0 or
0 mass0 charge
0
0n or n
Symbol for neutron
1
1H or 1p
Symbol for proton
1 1
Alpha Decay
Unstable nucleus emits an alpha particle.
Atomic # by 2. Mass # by 4.
220Fr 4 + 216At
Unstable nucleus emits an alpha particle.
Atomic # by 2. Mass # by 4.
87 2 85
220Fr 4 + 216At
Equation represents natural transmutation. 1 term on reactant side.
87 2 85
220Fr 4 + 216At
Balance nuclear equations using conservation of
atomic number & conservation of mass
number.
87 2 85
4 + 216=220
87 = 2 + 85
# of Half-Lives
Elapsed timeLength of H.L.
Half-Life Map
Mass Elapsed Time
Fraction Remainin
g
# of Half Lives
Start mass
0 1 0
1 X H.L. ½ 1
2 X H.L. ¼ 2
3 X H.L. 1/8 3
4 X H.L. 1/16 4
Decay Mode
Same as type of particle emitted
Average Atomic Mass
Weighted average of the masses of the naturally
occurring isotopes.
Artificial Transmutation
Particle “bullet” hits target nucleus & new isotope is produced.
2 terms on reactant side.
Artificial Transmutation
32S + 1n 32P + 1H16 0 15 1
bullettarget
Artificial Transmutation
Particle “bullet” may be proton or alpha particle. To react with a nucleus, must overcome + + repulsive forces by accelerating bullet to high speeds.Particle “bullet” may be a neutron. Neutrons have no charge, so no repulsive forces to overcome. No acceleration necessary.
Fission
Fission is division.
Large nucleus (U-235 or Pu-239) is split into 2 medium sized nuclei by a neutron bullet. Excess neutrons & a great deal of energy are also produced.
239Pu + 1n 90Sr + 147Ba + 3 1n
Fission
94 0 038 56
Fusion
Fusion: U for unite and U for sun.
Very small nuclei (H & He) are jammed together. Huge amounts of energy are released.
1H + 2H 3He
Fusion
1 1 2
Identify each of the rxns
a) 1n + 235U 142Ba + 91Kr + 3 1n + energy
b) 59Co + 1n 60Co
c) 3He + 1H 4He + 0e
d) 14C 14N + 0e
0 92 56 36 0
27 0 27
2 1 2 +1
6 7 -1
fission
Artificial transmutation
fusion
Natural transmutation