Radiation and Radioactivity Notes

Radioactivity

• Radioactivity originates from the nucleus of an atom.

• Elements with an atomic number of 19 or lower are generally stable due to nuclear forces.

• Elements above atomic number 20 tend to have more neutrons than protons to stabilize the nucleus.

• Radioisotopes have unstable nuclei, leading to the emission of particles or energy.

• Naming isotopes involves specifying the mass number (e.g., carbon-14).

Types of Radiation

• The primary types of radiation are alpha, beta, positron, and gamma radiation.

• Alpha and beta are particles, while gamma is energy.

Alpha Particles

• Alpha particles are equivalent to helium nuclei (42He).

• They have a mass number of 4 and an atomic number of 2.

Beta Particles

• Beta particles are high-energy electrons (0-1β).

• They have a mass number of 0 and an atomic number of -1.

• Beta particles can form through the conversion of a neutron into a proton and an electron.

Positrons

• Positrons are positively charged electrons (0+1e).

• They form when a proton changes into a neutron and a positron.

Gamma Rays

• Gamma rays are pure energy with no associated particle.

• They have mass and atomic numbers of 0.

Radiation Effects and Protection

• Radiation can ionize water molecules in the body, disrupting cellular reproduction.

• Alpha particles are large and can be blocked by paper or clothing but are harmful if inhaled.

• Beta particles require thicker clothing for shielding.

• Gamma rays need lead or concrete for effective protection.

Instability

• Radiation results from unstable nuclei, where repulsive forces between protons exceed attractive nuclear forces.