Science Terms and Definitions

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Acceleration

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The rate at which an object changes its velocity, including changes in speed or direction.

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Anion

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An ion with a negative charge, formed when an atom gains electrons.

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Atom

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The basic building block of matter; the smallest unit of an element that retains the chemical properties of that element, consisting of a nucleus (protons and neutrons) and surrounding electrons.

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Atomic Mass

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The average mass of all the isotopes of an element as they occur in nature.

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Atomic Number

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The number of protons in the nucleus of an atom, defining the element and its properties.

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Balanced Forces

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Two or more forces acting on an object that cancel each other out, resulting in no change in the object's motion.

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Cation

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An ion with a positive charge, formed when an atom loses electrons.

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Chemical Properties

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Properties of a substance that can only be observed during a chemical reaction, when the substance's composition is changed.

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Chemical Reaction

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A process that involves the rearrangement of atoms and molecules, resulting in the formation of new substances with different properties.

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Compound

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A pure substance made up of two or more different elements chemically combined in a fixed ratio.