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

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

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

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

Radioactive decay is represented with a Nuclear Equation

A nuclear equation must balance the mass numbers on both sides

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

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

Other types of nuclear decay include: Positron Emission and Electron Capture

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

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

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

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

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

Radioactive dating uses radioisotopes to determine the approximate age of an object

Nuclear radiation is used to detect and kill cancerous cells

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

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?

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 decayt1/2 = half-life