B
- background radiation
nuclear radiation that occurs naturally in the environment (p. 296)
- barometer
an instrument used to measure air pressure (p. 748)
- barred-spiral galaxy
a spiral galaxy in which spiral arms extend outward from a bar running through the center of the galaxy (p. 848)
- base
a compound that produces hydroxide ions (OH−) when dissolved in water; a proton acceptor (p. 242)
- batholith
the largest type of intrusive igneous rock mass (p. 696)
- battery
a device that converts chemical energy into electrical energy (p. 606)
- beta particle
an electron emitted by an unstable nucleus (p. 294)
- big bang theory
the theory of the beginning of the universe in an instant, billions of years ago, in an enormous explosion (p. 854)
- binary star
a star system with two stars that revolve around each other (p. 847)
- biology
the study of life and life processes (p. 4)
- biomass energy
the chemical energy stored in living things (p. 464)
- black hole
an object whose surface gravity is so great that not even electromagnetic waves can escape from it (p. 844)
- boiling point
the temperature at which a substance boils; the temperature at which vapor pressure is equal to atmospheric pressure (p. 47)
- Boyle's law
the inverse variation of the volume of a gas with its pressure if the temperature and the number of particles are constant (p. 79)
- buffer
a solution that is resistant to large changes in pH (p. 248)
- buoyancy
the ability of a fluid to exert an upward force on an object placed in it (p. 400)
- buoyant force
an upward force acting on an object in a fluid (p. 400)
C
- caldera
huge depression at the top of a volcano created when the central vent and magma chamber collapse after an eruption (p. 691)
- calorimeter
instrument used to measure thermal energy released or absorbed during a chemical or physical change (p. 478)
- camera
an optical instrument that records an image of an object (p. 582)
- carbohydrate
a compound composed of carbon, hydrogen, and oxygen in which the ratio of hydrogen to oxygen atoms is 2: 1 (p. 278)
- catalyst
a substance that affects the rate of a chemical reaction without being used up in the reaction (p. 215)
- cation
an ion with a positive charge (p. 160)
- central heating system
a heating system that heats many rooms from one central location (p. 489)
- centripetal force
a force that continuously changes the direction of an object to make it move in a circle (p. 381)
- chain reaction
a series of fission reactions triggered by neutrons released during the fission of a nucleus (p. 311)
- Charles's law
the direct proportion of the volume of a gas to its temperature (in kelvins) if the pressure and the number of particles of the gas are constant (p. 78)
- chemical bond
the force that holds atoms or ions together as a unit (p. 160)
- chemical change
change that occurs when a substance reacts and forms one or more new substances (p. 56)
- chemical energy
- chemical equation
a representation of a chemical reaction in which the reactants and products are expressed as formulas (p. 193)
- chemical formula
notation that shows what elements a compound contains and the ratio of the atoms or ions of these elements in the compound (p. 161)
- chemical property
any property that produces a change in the composition of matter (p. 54)
- chemical weathering
the process in which rock is broken down by chemical reactions (p. 710)
- chemistry
the study of the composition, structure, properties, and reactions of matter (p. 4)
- chromosphere
the middle layer of the sun's atmosphere, just outside the photosphere (p. 831)
- cinder cone
a small, steep-sided volcano formed from a combination of ash and cinders (p. 693)
- circuit breaker
a switch that opens when the current in a circuit is too high (p. 612)
- cirque
a large bowl-shaped valley carved out of a mountainside by a glacier (p. 720)
- cirrus clouds
thin, white, wispy clouds, often with a feathery or veil-like appearance (p. 763)
- clastic rocks
sedimentary rocks that form from the broken fragments of other rocks (p. 672)
- cleavage
a mineral's tendency to split along regular, well-defined planes (p. 668)
- climate
the long-term weather conditions of a place or region (p. 778)
- cloud
a dense, visible mass of tiny water droplets or ice crystals that are suspended in the atmosphere (p. 761)
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