numbers that appear before a formula in a chemical equation to show the relative proportions of each reactant and product (p. 194)

light waves having the same wavelength, with the crests and troughs lined up (p. 560)

a front that occurs when a cold air mass overtakes a warm air mass (p. 767)

a mixture that contains some particles that are intermediate in size between the small particles in a solution and the larger particles in a suspension (p. 44)

a chemical reaction in which a substance reacts rapidly with oxygen, often producing heat and light (p. 204)

a mass of rock, dust, and ice that partially vaporizes when it passes near the sun (p. 815)

any two colors of light that combine to form white light (p. 552)

any two colors of pigments that combine to make black pigment (p. 553)

a volcano that forms from a combination of lava and ash (p. 693)

a substance that is made from two or more simpler substances and can be broken down into those simpler substances (p. 40)

a combination of two or more simple machines that operate together (p. 435)

an area of a longitudinal wave where the particles of the medium are close together (p. 502)

a programmable device that can store and process information (p. 622)

a lens that is curved inward at the center and is thickest at the outside edges (p. 576)

a mirror that is curved inward (p. 572)

the amount of solute dissolved in a certain amount of solvent (p. 238)

the phase change in which a substance changes from a gas or vapor to a liquid (p. 90)

the transfer of thermal with no overall transfer of matter, within a material or between materials that are touching (p. 479); the transfer of electric charge by direct contact with a conductor (p. 602)

a material's ability to allow heat or electric charges to flow (p. 46)

light-sensitive neurons in the retina that detect color (p. 589)

a steady change in velocity (p. 345)

a group of stars that appears to form a pattern as seen from Earth (p. 846)

the interaction among two or more waves in which displacements combine to produce a wave with a larger displacement (p. 511)

the process in which the continents move slowly across Earth's surface (p. 677)

a thick sheet of ice that covers a large area of a continent or large island (p. 719)

the gently sloping plain that forms an apron of shallow water along the edges of most continents (p. 726)

an experiment in which only one variable, the manipulated variable, is deliberately changed at a time (p. 8)

the transfer of thermal energy when particles of a fluid move from one place to another (p. 480)

circulation of a fluid in a loop as the fluid alternately heats up and cools down (p. 481)

the region inside the sun where thermal engergy is transferred outward mainly by convection currents (p. 831)

a boundary at which tectonic plates collide (p. 682)

a ratio of equivalent measurements that is used to convert a quantity from one unit to another (p. 18)

a lens that is curved outward at the center and is thinnest at the outside edges (p. 576)

a mirror that is curved outward (p. 573)

the dense sphere at Earth's center, made mostly of iron and nickel (p. 663); the central region of the sun where nuclear fusion occurs (p. 830)

the change that Earth's rotation causes in the motion of objects (p. 759)

the transparent outer coating of the eye (p. 588)

the outermost layer of the sun's atmosphere, extending far above the chromosphere (p. 831)

a chemical bond in which two atoms share a pair of valence electrons (p. 166)

a bowl-shaped pit at the top of the central vent in a volcano (p. 691); a round depression in the surface of a planet, moon, asteroid, or comet, caused by the impact of a meteoroid (p. 797)

the highest point of a transverse wave (p. 501)

the angle of incidence that produces an angle of refraction equal to 90 degrees (p. 578)

the smallest possible mass of a fissionable material that can sustain a chain reaction (p. 311)

the rocky outer layer of Earth (p. 661)

solids whose particles are arranged in a lattice structure (p. 162)

puffy white clouds, usually with flat bottoms, that look like piles of cotton balls (p. 763)

a weather system with a center of low air pressure (p. 769)