Radioactivity

Atomic Structure

The atom consists of a small, dense, positively charged nucleus surrounded by negatively charged electrons. The nucleus contains protons and neutrons.

Protons

Subatomic particles with a positive charge found in the nucleus.

Neutrons

Subatomic particles with no charge found in the nucleus.

Electrons

Subatomic particles with a negative charge found in electron shells.

Nucleus

The central part of an atom, containing protons and neutrons.

Electron Shells

Energy levels at different distances from the nucleus where electrons exist.

Atomic Number

The number of protons in the nucleus, defining the element.

Mass Number

The total number of protons and neutrons in the nucleus.

Isotopes

Elements with the same atomic number but different mass numbers due to varying numbers of neutrons.

Valence Electrons

Electrons in the outermost occupied shell that determine chemical properties.

Ions

Atoms that have gained or lost electrons, resulting in a net positive or negative charge.

Radioactive Decay

The process where an unstable nucleus emits radiation and transforms into a more stable nucleus.

Alpha Particles

Made up of 2 protons and 2 neutrons, they have a +2 charge and are the least penetrating type of radiation.

Beta Particles

Fast moving electrons ejected from the nucleus during decay, they have a -1 charge and can pass through a few millimeters of aluminum.

Gamma Rays

High frequency electromagnetic waves emitted from the nucleus, they have no charge and are the most penetrating type of radiation.

Ionizing Radiation

Radiation that can remove electrons from atoms, causing cell damage.

Alpha Decay

The nucleus emits an alpha particle, reducing the atomic number by 2 and the mass number by 4.

Beta Decay

A neutron in the nucleus is converted into a proton, electron, and neutrino, increasing the atomic number by 1.

Gamma Decay

The nucleus emits a gamma ray photon, losing energy without any change to the composition of the nucleus.

Positron Decay

A proton is converted into a neutron, positron, and neutrino, decreasing the atomic number by 1.

Half-Life

The time it takes for the number of nuclei of a radioactive isotope to halve, or for the rate of decay to halve.

Uses of Radioactive Materials

Radiotracers in medicine, thickness and density gauges in industry, sterilization of food in agriculture, carbon dating in archaeology, and power generation in nuclear fission reactors.

Biological Effects

Ionizing radiation can damage cells and cause mutations that may lead to cancer.

Exposure Limits

Minimize exposure time, maximize distance from the source, use shielding, monitor radiation levels, and use protective equipment.

Nuclear Fission

The splitting of heavy nuclei like uranium-235 into lighter nuclei, releasing energy and more neutrons.

Nuclear Fusion

The joining together of light nuclei to make heavier ones, releasing energy.