Basic Atomic Structure

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Atom

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The smallest unit of ordinary matter that forms a chemical element.

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Proton

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

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Neutron

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A subatomic particle found in the nucleus of atoms that is neutral, meaning it has no charge.

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Electron

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A subatomic particle with a negative charge, found in all atoms and acting as the primary carrier of electricity in solids.

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Quark

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A fundamental constituent of matter observed in protons and neutrons, among other particles.

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Valence Electrons

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The electrons in the outer shell of an atom that are involved in forming bonds with other atoms.

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Atomic Number

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The number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.

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Mass Number

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The total number of protons and neutrons in an atomic nucleus.

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Isotopes

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

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Average Atomic Mass

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The weighted average mass of the atoms in a naturally occurring sample of the element.