nuclear transmutations - changing the atom’s identity
- 1st conversion done by Rutherford
- nuclear reactions can start by striking nuclei w/ particles
- particle accelerators - slams charged particles against nuclei
- needs high speed to overcome electrostatic repulsion between particles and nuclei
- not used for neutrons (not repelled by nuclei)
- transuranium elements - elements w/ atomic number greater than 92
Xenon-118 undergoes electron capture to become what?
- atomic number decreases by 1
- atomic mass stays the same
- 118Xe + -1e0 >> 118I
Carbon-14 undergoes betay decay to produce what?
- atomic number increases by 1
- atomic mass stays the same
- 14C >> 14N + -1e0
radioactive decay rates - 1st-order kinetic process
- half-life - time required for 1/2 of given quantity to react
- k = 0.693 / t1/2
- ln (Nt / N0) = -kt
An old piece of wood has carbon-14 activity of 11.7 disintegrations per minute per gram. Current carbon-14 activity is 15.3 disintegrations per minute per gram. The half-life of carbon-14 is 5714 years. How old is that old piece of wood?
- Given:
- t1/2 = 5714
- Nt = 11.7
- N0 = 15.3
- k = 0.693 / 5714 = 1.2 x 10-4
- ln (11.7 / 15.3) = -(1.2 x 10-4)t
- t = 2212 years old
Subject:
Subject X2:
