Half-Life

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Half-Life Noun

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[haf-lyf]

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Half-Life

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

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Example: This graph shows that after each half-life passes (x-axis), the percentage of the original substance (y-axis) is reduced by half.

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Nuclear Reaction Noun

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[noo-klee-er ree-ak-shun]

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Nuclear Reaction

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A process that involves a change in the nucleus of an atom, altering its number of protons or neutrons.

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Example: A large parent nucleus (Uranium-238) undergoes a nuclear reaction, splitting into a smaller daughter nucleus (Thorium-234) and an alpha particle.

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Radioactive Decay Noun

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[ray-dee-oh-ak-tiv dih-kay]

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Radioactive Decay

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The spontaneous process by which an unstable atomic nucleus loses energy by emitting radiation to become more stable.

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Example: An unstable parent nucleus (Uranium-238) releases an alpha particle, transforming into a new, more stable daughter nucleus (Thorium-234).

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Radiation Noun

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[ray-dee-ay-shun]

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Radiation

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The energy or particles emitted from the nucleus of a radioactive atom during the process of radioactive decay.

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Example: A large, unstable radioactive atom releases energy and smaller particles. This process, known as radiation, causes the atom to decay into a different element.

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Isotope Noun

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[ahy-suh-tohp]

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Isotope

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Atoms of the same element that have an identical number of protons but a different number of neutrons.

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Example: This image shows three forms of Carbon. They all have the same number of protons and electrons, but a different number of neutrons, which defines an isotope.

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Radioisotope Noun

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[ray-dee-oh-ahy-suh-tohp]

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Radioisotope

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An unstable isotope of a chemical element that undergoes radioactive decay, emitting radiation in the process.

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Example: A radioisotope, like uranium-238, is an unstable atom that decays by releasing particles, changing into a new, more stable atom like thorium-234.

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Radionuclide Noun

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[ray-dee-oh-noo-klahyd]

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Radionuclide

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An atom with an unstable nucleus, characterized by excess energy, which undergoes radioactive decay; a synonym for radioisotope.

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Example: An unstable radionuclide, like Uranium-238, decays by releasing a particle, transforming into a new, more stable element like Thorium-234.

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Parent Isotope Noun

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[pair-ent ahy-suh-tohp]

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Parent Isotope

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The original unstable radioactive isotope that undergoes decay to form a new, more stable daughter isotope.

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Example: An unstable parent nucleus (the starting atom) breaks apart, releasing a particle and changing into a more stable daughter nucleus (the resulting atom).

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Daughter Isotope Noun

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[daw-ter ahy-suh-tohp]

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Daughter Isotope

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The new, more stable isotope that is formed as a product of the radioactive decay of a parent isotope.

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Example: An unstable parent nucleus (Uranium-238) releases a particle, transforming into a new, more stable daughter nucleus (Thorium-234).

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Nucleus Noun

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[noo-klee-uhs]

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Nucleus

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The dense, positively charged central core of an atom, composed of protons and neutrons and containing nearly all its mass.

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Example: This diagram shows the parts of an atom, identifying the nucleus as the central core containing protons and neutrons, which is essential for understanding half-life.