Vocabulary Flashcards
(61 cards)
Acid
a compound that releases hydrogen ions when dissolved in water; has a pH less than 7
Absolute Zero
approxiamtely -273C, the lowest possible temperature
Algae
simple, one-celled plantlike organisms found in water or damp places; includes seaweeds, pond scum, and so on
Alloy
a substance composed of two or more metals
Atmosphere
the layer of air surrounding Earth
Atmospheric Pressure
the pressure exerted by the atmosphere on every part of Earth’s surface, approximately 10 newtons per square centimeter
Atom
the smallest part of an element that is recognizable as that element
Barometer
an instrument that measures atmospheric pressure
Base
a compound that releases hydroxide ions in water; has a pH greater than 7; is sometimes called an alkali
Boiling Point
the temperature at which additional thermal energy causes a substance to change from a liquid to a vapor
Calorie
a quantity of heat energy; the amount needed to raise the temperature of one gram of water 1 degree C. The large calorie, or “food calorie” is a kilocalorie (1000 calories)
Carbohydrate
an organic compound like sugar or starch that contains carbon, hydrogen, and oxygen in the ratio 1:2:1; the human body’s main source of energy
Carcinogen
a cancer-causing agent
Carnivore
a meat eater
Catalyst
a substance that speeds up a chemical reaction without being changed by the reaction
Cell
the lowest-level structure of any living organism that can perform all of the functions of life, including reproduction
Chlorophyll
the main pigment in plants that captures light energy during photosynthesis
Compound
a substance composed of two or more chemically bonded elements
Concentration
the exact amount of substance dissolved in a given amount of solvent; refers to a solution
Condensation
the process whereby a decrease in energy causes vapor particles to return to a liquid phase
Conductor
a material that allows heat or electricity to flow through it with minimal resistance
Control
a sample in which no variables are tested, thus serving as a basis for comparison
Control Variable
a variable that stays constant in an experiment, allowing the effect of another variable to be measured
Convection
the circulation of fluid caused by warm fluid rising and cool fluid sinking