| A | B |
|---|
| atom | basic unit of matter |
| nucleus | the center of the atom which contains the protons and neutrons; in cells, structure that contains the cell's genetic material (DNA) and controls the cell's activities |
| electron | negatively charged particle; located outside the atomic nucleus |
| element | substance consisting entirely of one type of atom |
| isotope | atom of an element that has a number of neutrons different from that of other atoms of the same element |
| compound | substance formed by the chemical combinatio of two or more elements in definite proportions |
| ionic bond | bond formed when one or more electrons are transferred from one atom to another |
| ion | atom that has a positive or negative charge |
| covalent bond | bond formed by the sharing of electrons between atoms |
| molecule | smallest unit of most compounds |
| van der Walls forces | a slight attraction that develops between the oppositely charged regions of nearby molecules |
| cohesion | attraction between molecules of the same substance |
| adhesion | attraction between molecules of different substances; in plants, attraction between unlike molecules |
| mixture | material composed of two or more elements or compounds that are physically mixed together but not chemically combined |
| solution | mixture of two or more substances in which the molecules of the substances are evenly distributed |
| solute | substance that is dissolved in a solvent to make a solution |
| solvent | substance in which a solute is dissolved to form a solution |
| suspension | mixture of water and undissolved materials |
| pH scale | measurement system used to indicated the concentration of hydrogen ions in solution; ranges from 0 to 14 |
| acid | compound that forms hydrogen ions in solution |
| base | compound that produces hydroxide ions in solution |
| buffer | weak acid or base that can react with strong acids or bases to help prevent sharp, sudden changes in pH |
| monomer | small unit that can join together with other small units to form polymers |
| polymer | large compound formed from combinations of many monomers |
| carbohydrate | compound made up of carbon, hydrogen, and oxygen atoms; major source of energy for the human body |
| monosaccharide | single sugar molecule |
| polysaccharide | large macromolecule formed from monosaccarides |
| lipid | macromolecule made mainly from carbon and hydrogen atoms; includes fats, oils, and waxes |
| nucleic acid | macromolecule containing hydrogen, oxygen, nitrogen, carbon, and phosphorus |
| nucleotide | monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base |
| ribonucleic acid (RNA) | single-stranded nucleic acid that contains the sugar ribose |
| deoxyribonucleic acid (DNA) | single-stranded nucleic acid that contains the sugar deoxyribose |
| protein | macromolecule that contains carbon, hydrogen, oxygen, and nitrogen; needed by the body for growth and repair and to make up enzymes |
| amino acid | compound with an amino group (-NH2) on one end and a carboxyl group (-COOH) on the other end |
| chemical reaction | process that changes one set of chemicals into another set of chemicals |
| reactant | element or compound that enters into a chemical reaction |
| product | element or compound produced by a chemical reaction |
| activation energy | energy needed to get a reaction started |
| catalyst | substance that speeds up the rate of a chemical reaction |
| enzyme | protein that acts as a biological catalyst |
| substrate | reactant of a enzyme-catalyzed reaction |
