Radioactive decay in a nutshell:
I.
Radioactivity: Atoms with an unstable
nucleus emit particles and energy. These
elements are called radioactive.
A. Radioactive isotope: an unstable version of a
stable element (represented on the Periodic table)
B. Synthetic elements: elements created artificially in
a cyclotron-usually radioactive
C. Radioactive decay: The breakdown of an unstable,
radioactive element from a parent element into a
daughter element.
D. Transmutation: The change of a Parent Element into a daughter element. The
identity of the daughter element is based on the type of decay.
1. Decay occurs in two forms: Alpha and Beta
a) Alpha Particle: 2 Protons and 2 Neutrons-Elements changes Atomic number
down 2, Mass down 4
b) Beta particle: A neutron loses an electron and becomes a proton-Atomic Number
goes up one, Mass doesn’t change.
c) Gamma radiation: The energy given off during Beta Decay.
E. Half-Life: the Rate of Decay-the amount of time it takes for half of a sample
of a radioactive element to decay.
II.
Recognizing Radiation
A.
Radiation from Unstable isotopes is known as Ionizing Radiation
1.
B.
It has enough energy to knock electrons off of an atom.
Measuring radiation
1.
A Geiger counter can be used to sense and measure radiation
a)
The radiation creates an electric current in the Geiger counter
that can be measured
b)
Photographic film is also sensitive to radiation and will turn dark
if exposed to too much radiation
2.
Radiation is measured by several units: Curie, roentgen, rad, rem and
millirem.
3.
The critical measure is by Dose:
a)
There are 3 factors:
(1)
Time-Like the sun’s rays, radiation’s effect is accumulated over
time
(2)
Shielding-different types of radiation are stopped by different
materials (Alpha-Paper; Beta-Aluminum foil; Gamma-reinforced
concrete, leaded glass)
(3)
Distance-Even air can supply some shielding, so how near to the
source you are is important
4.
Safe dosages:
a)
Radiation on humans is measured in millirems.
b)
The damage of small doses of radiation can be repaired by our
body systems
c)
Most humans receive 150-200 millirems per year, and anything
less than 5000 millirems per year is considered low-level.
III.
d)
100,000 millirems will cause radiation sickness
e)
500,000 millirems over 3 days will kill a person
Uses:
A.
Radioactive isotope tracing-small amounts of an isotope are put into
a body and can be followed by x-ray or other detection device
B.
X-Rays-low level radiation that can penetrate soft tissue, but not
bones.
C.
Radioactive dating: Carbon-14. Uranium, Rubidium and Potassium
are all used to date fossils, rocks, moon rocks, old bones, etc.
D.
Irradiated food kills germs, allowing for extended storage.
E.
Nuclear reactors: Generate heat, making steam, spinning turbines to
create electricity.