Glossary

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substitution reaction: A reaction in which one atomThe smallest particle of an element that can be involved in chemical combination with another element; an atom consists of protons and neutrons in a tiny, very dense nucleus, surrounded by electrons, which occupy most of its volume. or functional groupA set of atoms in a molecule that confer on the molecule a characteristic set of physical and chemical properties. is replaced by another (distinguished from an addition reactionA reaction in which two moleular-scale species combine to form a single molecular-scale species (distinguished from a substitution reaction).).

Term of the Day

An estimate of the size of an ionAn atom or covalently bonded set of atoms that carries an overall net charge. in an ionic compoundA compound containing oppositely charged ions held together by electrostatic attraction. Usually the ions are in a crystal lattice with positive ions surrounded by negative ions and negative ions surrounded by positive ions.; found from the internuclear distanceThe distance between the nuclei of nearest-neighbor atoms or ions in an element or compound. Bond distances and ionic radii are calculated from this quantity because atoms have no discrete edges. between ions in a crystal latticeAn orderly, repeating arrangement of points in 3-D space in which each p;oint has surroundings identical to every other point. A crystal's constituent atoms, molecules, and ions are arranged about each lattice point..