Download Radioactive Decay

HALF-LIFE
• Amount of time it takes for half of the radioactive substance to
decay
• Continually losing 50% of the remaining substance every halflife
Targets:
• I can find the half-life of a radioactive substance
• I can figure out how much of the substance is left after 1, 2, 3,
4, etc. half-lifes
• I can figure out how old a substance is using the half-life
• I can interpret a graph on half-life
RADIOACTIVE DECAY
•What makes an atom
stable/unstable?
• The number of neutrons
in the nucleus can make
an atom UNSTABLE
WHAT DO YOU THINK OF?
• Radioactivity: Substances spontaneously emit
radiation
• Radiation: rays and particles emitted by radioactive
material
• Radioactive atoms go through changes that alter
their identity – aka changes from one atom to
another
• How can this happen?
• There must be a change in
the number of protons for an
atom to change identity
• Unstable nuclei lose energy to
become more stable = radioactive
decay
• Form stable atoms after they
release energy
ALPHA ( ) DECAY
1) The nucleus of an atom splits into two parts.
2) One of these parts (the alpha particle) goes
zooming off into space.
3) The nucleus left behind has its atomic number
reduced by 2 and its mass number reduced by
4 (that is, by 2 protons and 2 neutrons).
4) Low level of danger
ALPHA ( ) DECAY
What is the mass of an alpha particle?
ALPHA ( ) DECAY
• Alpha radiation is not very penetrating—a single
sheet of paper will stop an alpha particle.
ALPHA ( ) DECAY
BETA ( ) DECAY
1) A neutron changes to proton
2) It emits an electron which goes zooming
off into space.
3) The atomic number goes UP by one and
mass number remains unchanged.
4) Moderate level of danger
BETA ( ) DECAY
BETA ( ) DECAY
GAMMA (G ) DECAY
1) High energy, high level of danger
2) No mass and no charge
3) Emission does not result in a new
atom
GAMMA (G ) DECAY