Nuclear Particles

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Nucleus Noun

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[noo-klee-uhs]

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Nucleus

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

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Example: This diagram shows the nucleus as the central core of an atom, containing a dense cluster of protons and neutrons.

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Proton Noun

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[proh-ton]

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Proton

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A stable subatomic particle with a positive electric charge, found in the nucleus of every atom.

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Example: This diagram shows a proton as a positively charged particle located inside the atom's central nucleus, along with a neutron.

Front

Neutron Noun

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[noo-tron]

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Neutron

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A subatomic particle with no net electric charge, found in the nucleus of an atom alongside protons.

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Example: This diagram shows a neutron, a particle with no charge, located inside the atom's central nucleus along with protons.

Front

Nucleon Noun

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[noo-klee-on]

Back

Nucleon

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A collective name for a proton or a neutron, the particles that make up the atomic nucleus.

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Example: This diagram shows that nucleons are the particles inside an atom's nucleus, which are the protons and neutrons.

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Fission Noun

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[fish-uhn]

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Fission

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A nuclear reaction in which a heavy nucleus splits into smaller parts, often producing free neutrons and photons.

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Example: A neutron hits a large atom (Uranium 235), causing it to split into smaller elements, releasing more neutrons and a large amount of energy.

Front

Fusion Noun

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[fyoo-zhuhn]

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Fusion

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A nuclear reaction where two or more atomic nuclei combine to form different atomic nuclei and subatomic particles.

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Example: Two light atomic nuclei, Deuterium and Tritium, merge to create a heavier nucleus, Helium, releasing a neutron and a massive amount of energy.

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Atomic Number Noun

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[uh-tom-ik num-ber]

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Atomic Number

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The number of protons in an atom's nucleus, which uniquely identifies a chemical element and is denoted by Z.

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Example: This diagram of an oxygen atom shows 8 protons in its nucleus. The number of protons (8) is the atomic number for the element oxygen.

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Mass Number Noun

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[mas num-ber]

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Mass Number

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The total number of protons and neutrons, collectively known as nucleons, in an atomic nucleus, denoted by A.

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Example: This diagram shows a helium atom's nucleus has 2 protons and 2 neutrons, which equals the mass number (4) in the element's symbol.

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Isotope Noun

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[ahy-suh-tohp]

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Isotope

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Variants of a chemical element which differ in neutron number but have the same number of protons.

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Example: Isotopes are versions of an element with the same number of protons but different numbers of neutrons, as shown by the hydrogen atoms with 0, 1, and 2 neutrons.

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Atomic Mass Unit Noun

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[uh-tom-ik mas yoo-nit]

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Atomic Mass Unit

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A unit of mass for atomic weights, defined as one-twelfth of the mass of a single carbon-12 atom.

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Example: An atom's mass is concentrated in its nucleus. The Atomic Mass Unit (AMU) is based on the mass of protons and neutrons in the nucleus.