| Term | Definition |
|---|
| acid | any substance that forms hydrogen ions (H+) in water and has a pH below 7 |
| atom | smallest particle of an element that has the characteristics of that element; basic building block of all matter |
| base | any substance that forms hydroxide ions (OH-) in water and has a pH above 7 |
| compound | substance composed of atoms of two or more different elements that are chemically combined |
| covalent bond | chemical bond formed when two atoms share electrons |
| element | substance that can't be broken down into simpler chemical substances |
| ion | atom or group of atoms that gain or lose elctrons; has an electrical charge |
| ionic bond | chemical bond formed by the attractive forces between two ions of opposite charge |
| isotope | atoms of the same element that have different numbers of neutrons in the nucleus |
| metabolism | all of the chemical reactions that occur within an organism |
| mixture | combination of substances in which individual components retain their own properties |
| molecule | group of atoms held together by covalent bonds; has no overall charge |
| nucleus | positively charged center of an atom composed of neutrons and positively charged protons, and surrounded by negatively charged electrons |
| pH | measure of how acidic or basic a solution is; the scale ranges from below 0 to above 14; solution with pH above 7 is basic and a pH below 7 is acidic |
| solution | mixture in which one or more substances (solutes) are distributed evenly in another substances |
| diffusion | net, random movement of particles from an area of higher concentration to an area of lower concentration, eventually resulting in even distribution |
| dynamic equilibrium | result of diffusion where there is continuous movement particles but no overall change in concentration |
| hydrogen bond | weak chemical bond formed by the attraction of positively charged hydrogen atoms to other negatively charged atoms |
| polar molecule | molecule with an unequal distribution of charge, resulting in the molecule having a positive end and a negative end |
| amino acid | basic building block of protein molecule |
| carbohydrate | organic compound used by cells to store and release energy; composed of carbon, hydrogen, and oxygen |
| enzyme | type of protein found in all living things that changes the rate of chemical reactions |
| isomer | compounds with the same simple formula but different three-dimensional structures resulting in different physical and chemical properties |
| lipid | large organic compounds made mostly of carbon and hydrogen with a small amount of oxygen; examples are fats, oils, waxes, and steroids; are insoluble in water and used by cells for energy storage, insulation, and protective coatings, such as in membranes |
| nucleic acid | complex biomolecules, such as RNA and DNA, that store cellular information in cells in the form of a code |
| nucleotide | subunits of nucleic acid formed from a simple sugar, a phosphate group, and a nitrogenous base |
| peptide bond | covalent bond formed between amino acids |
| polymer | large molecule formed when many smaller molecules bond together |
| protein | large, complex polymer essential to all life composed of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur; provides structure for tissues and organs and helps carry out cell metabolism |
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