| Matter | Anything that has mass and takes up space. |
| Model | An explanation or representation of something that cannot be seen. |
| Element | A collection of atoms that all have the same number of protons. |
| Molecules | Chemicals that result from atoms linking together. |
| Physical Change | A change that affects the appearance but not the chemical makeup of a substance. |
| Chemical Change | A change that alters the makeup of the elements or molecules of a substance. |
| Phase | One of three forms -- solid, liquid, or gas -- which every substance is capable of attaining. |
| Diffusion | The random motion of molecules from an area of high concentration to an area of low concentration. |
| Concentration | A measurement of how much solute exists within a certain volume of solvent. |
| Semipermeable Membrane | A membrane that allows some molecules to pass through but does not allow other molecules to pass through. |
| Osmosis | The tendency of a solvent to travel across a semipermeable membrane into areas of higher solute concentration. |
| Catalyst | A substance that alters the speed of a chemical reaction but is not used up in the process. |
| Organic Molecule | A molecule that contains only carbon and any of the following: hydrogen, oxygen, nitrogen, sulphur, and / or phosphorous. |
| Biosynthesis | The process by which living organisms produce larger molecules from smaller ones. |
| Isomers | Two different molecules that have the same chemical formula. |
| Monosaccharides | Simple carbohydrates that contain 3 to 10 carbon atoms. |
| Disaccharides | Carbohydrates that are made up of two monosaccharides. |
| Polysaccharides | Carbohydrates that are made up of more than two monosaccharides. |
| Dehydration Reaction | A chemical reaction in which molecules combine by removing water. |
| Hydrolysis | Breaking down complex molecules by the chemical addition of water. |
| Hydrophobic | Lacking any affinity to water. |
| Saturated Fat | A lipid made from fatty acids that have no double bonds between carbon atoms. |
| Unsaturated Fat | A lipid made from fatty acids that have at least one double bond between carbon atoms. |
| Peptide Bond | A bond that links amino acids together in a protein. |
| Hydrogen Bond | A strong attraction between hydrogen atoms and certain other atoms (usually oxygen or nitrogen) in specific molecules. |
