Radioactivity key terms

Rutherford scattering

A process where alpha particles are directed at a thin gold foil, leading to observations of deflections that suggest the presence of a small, dense nucleus.

alpha particle

A type of radiation consisting of two protons and two neutrons, emitted during radioactive decay, which can cause significant ionization in materials.

Rutherford scattering

The experimental observation of alpha particles being deflected by a thin gold foil, indicating the presence of a small, dense nucleus.

small dense nucleus

A central core of an atom that contains most of its mass and positive charge, supported by scattering evidence from Rutherford's experiments.

scattering angle

The angle at which alpha particles are deflected when they encounter a nucleus, related to the nuclear charge and distance of closest approach.

distance of closest approach

The minimum distance between the alpha particle and the nucleus during scattering, influenced by the nuclear charge.

Plum Pudding Model

An early 20th-century atomic model proposed by J.J. Thomson, suggesting that atoms are composed of a positively charged 'soup' with negatively charged electrons embedded within.

Rutherford Scattering

An experiment conducted by Ernest Rutherford that demonstrated the existence of a small, dense nucleus in atoms, leading to the rejection of the plum pudding model.

Alpha radiation

A type of ionizing radiation consisting of alpha particles, which are made up of two protons and two neutrons, emitted from the nucleus of an unstable atom.

Beta radiation

A type of ionizing radiation consisting of beta particles, which are high-energy, high-speed electrons or positrons emitted from a decaying atomic nucleus.

absorption experiments

Experiments designed to measure how different materials absorb nuclear radiation, providing insights into the properties of alpha, beta, and gamma radiation.

nuclear radiation

Radiation emitted from the nucleus of an unstable atom, which can include alpha particles, beta particles, and gamma rays.

Inverse-square law

The intensity of gamma radiation is inversely proportional to the square of the distance from the source.

Gamma radiation intensity

The power per unit area carried by gamma radiation, which decreases as the distance from the source increases.

Inverse-Square Law

The intensity of gamma radiation is inversely proportional to the square of the distance from the source.

Gamma Radiation Intensity

The power per unit area carried by gamma radiation, which decreases as the distance from the source increases.

Radioactive decay

The process by which an unstable atomic nucleus loses energy by emitting radiation, occurring randomly and following an exponential decay pattern.

Exponential decay

A decrease in quantity at a rate proportional to its current value, commonly observed in radioactive decay, where the activity decreases over time.

decay constant

The decay constant (λ) is a probability rate at which a radioactive substance decays, measured in units of time^-1.

activity

Activity (A) is the rate at which a sample of radioactive material decays, measured in becquerels (Bq), where 1 Bq equals one decay per second.

half-life

The time required for half of the radioactive nuclei in a sample to decay.

remaining activity

The activity of a radioactive sample after a certain period of time, calculated based on the initial activity and the number of half-lives that have passed.

decay graph

A graphical representation showing the decrease in the number of radioactive nuclei over time, illustrating the exponential nature of radioactive decay.

half-life

The time required for half of the radioactive nuclei in a sample to decay, indicating the rate of decay and stability of the isotope.

neutron-proton ratio

The ratio of the number of neutrons to the number of protons in a nucleus, which helps determine nuclear stability.

nuclear stability

The condition of a nucleus that remains unchanged over time, influenced by the balance of forces between protons and neutrons.

decay mode

The specific type of radioactive decay a nucleus undergoes, such as alpha, beta, or gamma decay.

neutron-proton ratio

The ratio of neutrons to protons in a nucleus, which influences its stability and decay mode.

Alpha decay

A type of radioactive decay in which an atomic nucleus emits an alpha particle, consisting of two protons and two neutrons, resulting in a new element with a lower atomic number.

Beta decay

A type of radioactive decay in which a beta particle (an electron or positron) is emitted from an atomic nucleus, resulting in a change of one neutron into a proton or vice versa, altering the atomic number of the element.