1. Radioactivity

2. Isotopes Isotopes of an atom contain different numbers of neutrons
The ratio of protons to neutrons is related to the stability of the isotope
The Band of Stability displays the ratios of protons to neutrons in a stable nucleus

4. Radioisotopes
An isotope with an unstable nucleus is known as a Radioisotope
A radioisotope will undergo a spontaneous change in the nucleus in order to form a stable nucleus
This process is known as Radioactivity or Radioactive Decay

5. Radioactivity
Radioactive nuclei give off particles and waves of electromagnetic radiation
Radioactivity always results in a more stable nucleus
Radioactivity also always results in a new element
A Transmutation is a change in the identity of an atom after a change of the protons in the nucleus

6. Radioactivity
The three main types of radiation are: alpha radiation, beta radiation, and gamma radiation

7. Alpha Radiation
Alpha radiation results in the release of an Alpha Particle
An alpha particle is a helium nucleus: two protons and two neutrons
The mass of an alpha particle is 4 amu, and the charge is 2+
Alpha particles are low in energy and can be shielded by paper or clothing

9. Nuclear Equations
Radioactive decay is represented with a Nuclear Equation
A nuclear equation must balance the mass numbers on both sides

10. Alpha Radiation

11. Beta Radiation
Beta radiation is the result of the breakdown of a neutron
Beta Radiation occurs when a neutron is converted to a proton and an electron
The proton remains in the nucleus, and the electron is released from the atom
Beta particles are negatively charged
Beta radiation is stronger than alpha radiation, but can be blocked by aluminum foil or wood

12. Beta Radiation

14. Beta Radiation

15. Gamma Radiation
A high energy photon released by a radioisotope is called a gamma ray
Gamma rays are often emitted along with an alpha or beta particle
Gamma rays are very high in energy and must be shielded by lead or concrete

16. Gamma Radiation

20. Other types of Radioactive Decay
Other types of nuclear decay include: Positron Emission and Electron Capture

21. Positron Emission
If the ratio of protons to neutrons is too high, an atom may emit a Positron
A positron is a positively charged particle with the mass of an electron
The result of a positron emission is one more neutron and one less proton in the nucleus

23. Electron Capture
If the ratio of Protons to Neutrons is too high, the atom may undergo Electron Capture
In electron capture, an electron is taken into the nucleus from its own atom
The result of electron capture is one less proton, one less electron, and one more neutron

25. Nuclear Fission
When a radioisotope is bombarded with neutrons, it may split into smaller atoms
This process is called Fission
The fission process releases a high amount of energy
Fission often results in a chain reaction
Nuclear fission is the process used in nuclear power plants
Uncontrolled chain reactions are the basis of atomic bombs

27. Nuclear Fusion
Nuclear fusion occurs when nuclei combine to create a nucleus of greater mass
Nuclear fusion releases more energy than fission reactions
Nuclear fusion is responsible for the energy provided by the sun

29. Radiation Detection Radiation can be measured by several devices
Film badges use exposure of film to measure radiation exposure
Geiger Counters detect radiation through electric pulses in ionized gas
Scintillation counters measure radiation from substances that emit visible light when energy is absorbed

31. Uses of Radiation
Radioactive dating uses radioisotopes to determine the approximate age of an object
Nuclear radiation is used to detect and kill cancerous cells

32. Rate of Decay No two radioisotopes decay at the same rate
A Half-Life(t1/2) is the time required for half of the atoms of a radioisotope to decay
A half-life can be as short as a fraction of a second, or billions of years

35. Calculations with Half-Lives
The amount of radioactive isotope remaining can be calculated:    
Nt = No x (0.5)number of half-lives
Where:     Nt = amount of radioisotope remaining     No = original amount of radioisotope     number of half-lives = time ÷ half-life
Manganese-56 is a beta emitter with a half-life of 2.6 h. What is the mass of manganese-56 in a 1.0-mg sample of the isotope at the end of 10.4 h?

36. Calculating Half-Lives
To Calculate a Half Life:
t1/2 = (.301)T
log(N0/Nt)
Where:     Nt = amount of radioisotope remaining     No = original amount of radioisotope
T = Time of decay
t1/2 = half-life