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the center of the atom which contains the protons and neutrons; in cells, structure that contains the cell's activities.
atom of an element that has a number of neutrons different from that of other atoms of the same element.
substance formed by the chemical combination of two or more elements in definite proportions.
van der Waals forces
a slight attraction that develops between the oppositely charged regions of nearby molecules.
attraction between molecules of different substances; in plants, attraction between unlike molecules.
material composed of two or more elements or compounds that are physically mixed together but not chemically combined.
mixture of two or more substances in which the molecules of the substances are evenly distributed.
measurement system used to indicate the concentration of hydrogen ions (H+) in solution; ranges from 0 to 14
weak acid or base that cna react with strong acids or bases to help prevent sharp, sudden changes in pH.
compound made up of carbon, hydrogen, and oxygen atoms; major source of energy for the human body.
monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base.
macromolecule that contains carbon, hydrogen, oxygen, and nitrogen; needed by the body for growth and repair and to make up enzymes.
compound with an amino group (-NH2) on one end and a carboxyl group (-COOH) on the other end.
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