3. • French physicist, Antoine Henri Becquerel discovered that
uranium compounds gave off invisible rays.
• He told Marie Curie, he asked her to isolate , or separate the
new element.
• Currie and her husband Pierre, began experiments in their
home laboratory. After a few months, the isolated an element
they called polonium. Several months later they isolated
radium.
• They discovered that these two elements give off invisible
particles, or rays – a quality they named radioactivity.
• Later, Ernest Rutherford studied radium, and found that the
radiation, or energy released from radioactive substances
exists in three forms: alpha particles, beta particles, and
gamma rays.
4. • Alpha particles are charged atomic particles.
• Each particle is made up of two protons and two neutrons from the
nucleus.
• Relatively large, so it does not penetrate materials very far.
• It can be stopped by a sheet of paper or aluminum foil or 5cm of
air.
• When an alpha particle leaves an atom, the atom changes into
another type of atom.
5. • Beta particles are negatively charged particles from the
atom.
• They are smaller than alpha particles and have only one negative
charge.
• Beta particles have 100 times more penetrating ability than alpha
particles.
• Require 2 in of aluminum foil to stop them
• The loss of beta particles also changes the first atom into another
type of atom
6. • Gamma rays are not charged particles.
• They are just very high-energy X-rays.
• Gamma rays have more penetrating ability than alpha or beta
particles.
• The can pass through a foot of concrete or through the human
body.
• Over exposure to gamma rays is harmful to living things because
the rays can hit cells inside the body of an organism and destroy
them.
8. • The nucleus of each radioactive element gives off a
random number of particles, or rays, in a fixed amount of
time.
• This process is called radioactive decay.
• This time it takes for half the atoms of a sample to break
down or decay is called half-life.
• EXAMPLE:
• It takes 20 minutes for half the atoms of Carbon 11 to break down.
• Carbon 11 has a half-life of 20 minutes. There are only 4 grams of
Carbon 11 left. It has changed into another type or atom (boron II)
• This change has occurred because the atoms have lost alpha and
beta particles.
• Different radioisotopes have different half-lives.
9. • Law of Conservation of Mass-Energy
• States that matter can change into energy, and energy can change
into matter.
• During these changes any amount of matter lost it changed into
energy, and any energy lost is changed into matter
• First proposed by Albert Einstein, E=mc²
10. • In 1939 scientists discovered that the nuclei of uranium atoms
could be split into smaller nuclei in a process called fission
• Fission is accomplished by hitting the nuclei with slow-moving
neutrons.
• There is no change in the total number of protons and
neutrons, there is a change in the total mass
• The small nuclear mass that is missing changes into
energy, called nuclear energy.
• A chain reaction is a continuous series of nuclear fissions
• Controlled chain reactions in power plants allow us to capture
the energy given off during nuclear reactions without an
explosion
11. • Fusion puts atoms together, or fusing them.
• A small loss of mass, which comes out of the reaction as
a large amount of energy.
• Very high temperatures of about 10 million degree
Celsius are necessary for fusion to take place.
12. • Objectives:
• Identify the dangers associated with nuclear energy
• Identify the benefits of nuclear energy
13. • Nuclear Reactors – produce large amounts of energy
using small amounts of fuel.
• Businesses use nuclear energy to check structures and
manufactured goods for flaws or weak points.
• Scientific researchers in the fields of biology and
paleontology use nuclear energy to learn more about
what they study.
• Medicine uses nuclear energy to diagnose and treat a
wide variety of problems and illnesses.
A proton accelerator uses nuclear particles to
bombard cancerous tissue and destroy it.
