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, Gamma Separated 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.

2 He or 2  Symbol for alpha radiation 4 4

2 He or 2  Same as the nucleus of a helium atom 4 4

2 He or 2  Mass = 4 amu Charge =

-1 e or -1  or  - or  Symbol for beta particle 00

-1 e or -1  or  - or  Fast moving electron originating from nucleus 00

-1 e or -1  or  - or  Mass = “zero” Charge = -1 00

+1 e or +1  or  + Symbol for positron. 00

+1 e or +1  or  + Mass = “zero.” Charge = +1. Positive electron 00

0  or  Symbol for gamma radiation. 0

0  or  0 mass 0 charge 0

0 n or n Symbol for neutron 1

1 H or 1 p Symbol for proton 1 1

Alpha Decay Unstable nucleus emits an alpha particle. Atomic #  by 2. Mass #  by 4.

220 Fr  4  At Unstable nucleus emits an alpha particle. Atomic #  by 2. Mass #  by

220 Fr  4  At Equation represents natural transmutation. 1 term on reactant side

220 Fr  4  At Balance nuclear equations using conservation of atomic number & conservation of mass number =220 87=

# of Half-Lives Elapsed time Length of H.L.

Half-Life Map MassElapsed Time Fraction Remaining # of Half Lives Start mass010 1 X H.L.½1 2 X H.L.¼2 3 X H.L.1/83 4 X H.L.1/164

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 32 S + 1 n  32 P + 1 H 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.

239 Pu + 1 n  90 Sr Ba n Fission

Fusion Fusion: U for unite and U for sun. Very small nuclei (H & He) are jammed together. Huge amounts of energy are released.

1 H + 2 H  3 He Fusion 1 1 2

Identify each of the rxns a) 1 n U  142 Ba + 91 Kr n + energy b) 59 Co + 1 n  60 Co c) 3 He + 1 H  4 He + 0 e d) 14 C  14 N + 0 e fission Artificial transmutation fusion Natural transmutation