<p>ACT Words Updated for Intro to science and physical science test!</p><p>O Absolute zero: lowest-possible temperature, approximately -273 </p><p> degrees C or 0 degrees K (elvin)</p><p>O Alloy: a substance composed of two or more metals </p><p>(synonym: amalgam)</p><p>O Barometer: an instrument used to measure atmospheric pressure</p><p>O Boiling point: the temperature at which additional thermal energy </p><p> causes a substance to change from liquid to vapor</p><p>O Concentration: The exact amount of substance dissolved in a given </p><p> amount of solvent; refers to a solution</p><p>O Catalyst: a substance that speeds up a chemical reaction without being</p><p> changed by the reaction</p><p>O Diffusion: The scattering of light; the spreading of a liquid or gas from</p><p> areas of higher concentration to areas of lower concentration</p><p>O Infrared radiation: electromagnetic waves whose wavelength is longer </p><p> than that of visible light</p><p>O Ion: a molecule or atom that has become charged by either gaining or </p><p> losing an electron</p><p>O Isotope: a type of element with the same number of protons per atom</p><p> but different number of neutrons O Melting point: the temperature at which a substance changes from </p><p> solid to liquid state</p><p>O Neutron: an atomic particle that has no charge</p><p>O Osmosis: the movement of liquid through a membrane</p><p>O PH: a scale from 1-14; represents the acidity or alkalinity of a </p><p> solution; low values are acidic, 7 is neutral, high values is alkaline</p><p>O Proton: a positively charged atomic particle</p><p>O Ultraviolet radiation: electromagnetic waves with wavelength shorter </p><p> than that of visible light</p><p>O Vapor: the gaseous for of liquid</p><p>O X ray: Electromagnetic radiation with wavelength shorter than </p><p> ultraviolet radiation</p><p>O Frequency: The number of cycles per unit time of a repeating </p><p> phenomenon</p><p>O -Insulator: a substance that blocks the flow of heat or electricity Required words for all students are below…</p><p>O 1- Atom: The smallest part of an element that is recognizable as that</p><p> element</p><p>O 2-Acid : compound with a pH less than 7</p><p>O 3-Base: compound with a pH greater than 7 (synonym: alkali)</p><p>O 7-Condensation: The process whereby a decrease in energy causes </p><p> vapor particles to return to a liquid phase</p><p>O 9-Compound: a substance composed of two or more chemically </p><p> bonded elements</p><p>O 10-Conductor: a material that allows heat or electricity to flow </p><p> through it with minimal resistance</p><p>O 11-Control Group: a sample or group in which no variables are tested. The control serves as a basis for comparison to the tested group. Example: 1. Testing how watering affects plants- test group gets different amounts of water. The Control group will not get water.- Scientists will compare the control group to the group that was tested ( got water in this case) EX: same height for egg drop O 12-Control variable : a variable that stays constant in an experiment, </p><p> allowing the effect of another variable to be measured</p><p>O 13-Density In a physics sense, the amount of mass per unit volume; in</p><p> a more general sense, the quantity per unit area or volume</p><p>O 16-Electron: a negatively charged part of the atom</p><p>O 17-Element:A substance consisting of exactly one type of atom</p><p>O 19-Evaporation: the changing of liquid into gas</p><p>O 23-Hypothesis: A statement that is a proposed explanation of a scientific phenomenon or event ( Testable) O 24-Insulator: a substance that blocks the flow of heat or electricity</p><p>O 25-Kinetic energy: the energy of an object in motion</p><p>O 26-Molecule: The smallest unit of a chemical compound</p>