Radioactive Decay

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Radioactivity Noun

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[ray-dee-oh-ak-tiv-i-tee]

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Radioactivity

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The spontaneous emission of energetic particles or waves from unstable atomic nuclei as they undergo decay.

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Example: This graph shows that as a radioactive substance decays, the amount remaining is halved after each 'half-life' period, starting from 100%.

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Ionizing Radiation Noun

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[eye-on-eye-zing ray-dee-ay-shun]

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Ionizing Radiation

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Energetic particles or waves with enough energy to remove tightly bound electrons from atoms, thereby creating ions.

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Example: This diagram shows that different types of ionizing radiation have different penetrating powers: alpha is stopped by paper, beta by aluminum, and gamma by lead.

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Alpha Radiation Noun

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[al-fuh ray-dee-ay-shun]

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Alpha Radiation

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A type of ionizing radiation composed of fast-moving helium-4 nuclei, which are also known as alpha particles.

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Example: An unstable parent nucleus releases an alpha particle (two protons and two neutrons), transforming into a new, smaller daughter nucleus.

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Beta Radiation Noun

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[bay-tuh ray-dee-ay-shun]

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Beta Radiation

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A form of ionizing radiation consisting of high-speed electrons or positrons that are emitted during radioactive decay.

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Example: This diagram shows a neutron in a Carbon-14 nucleus changing into a proton, transforming the atom into Nitrogen-14 and releasing a high-energy electron (beta radiation).

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Gamma Radiation Noun

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[gam-muh ray-dee-ay-shun]

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Gamma Radiation

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High-energy electromagnetic radiation, consisting of photons, emitted from an atomic nucleus during a transition to a lower energy state.

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Example: An excited atomic nucleus releases energy by emitting a high-energy gamma photon, transitioning to a more stable, relaxed state without changing its particle count.

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Half-life Noun

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[haf-lyf]

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Half-life

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The characteristic time required for exactly half of the radioactive atoms in a given sample to undergo decay.

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Example: This graph shows that for each half-life that passes, the amount of the radioactive substance (Co-60) decreases by half, from 10g to 5g, then to 2.5g, and so on.

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Isotope Noun

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[eye-so-tope]

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Isotope

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Variants of a particular chemical element which have the same number of protons but different numbers of neutrons.

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Example: This image shows three forms of hydrogen, called isotopes. They all have one proton, but different numbers of neutrons (zero, one, and two).

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Alpha Decay Noun

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[al-fuh dee-kay]

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Alpha Decay

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A type of radioactive decay in which an atomic nucleus emits an alpha particle, transforming into a different nucleus.

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Example: An unstable atomic nucleus (Uranium-235) releases an alpha particle (two protons and two neutrons) to become a new, smaller nucleus (Thorium-231).

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Beta Decay Noun

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[bay-tuh dee-kay]

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Beta Decay

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A radioactive process where a beta particle is emitted from an atomic nucleus, changing a neutron to a proton or vice-versa.

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Example: In an unstable atom's nucleus, a neutron changes into a proton, and an electron (a beta particle) is released.

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Gamma Decay Noun

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[gam-muh dee-kay]

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Gamma Decay

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A process where an excited atomic nucleus transitions to a lower energy state by emitting a high-energy photon (gamma ray).

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Example: An unstable, high-energy 'Parent' nucleus releases a gamma ray (energy) to become a stable, lower-energy 'Daughter' nucleus without changing its particle count.