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Chemistry: Atoms First

Key Terms

Chemistry: Atoms FirstKey Terms

accuracy
how closely a measurement aligns with a correct value
atom
smallest particle of an element that can enter into a chemical combination
Celsius (°C)
unit of temperature; water freezes at 0 °C and boils at 100 °C on this scale
chemical change
change producing a different kind of matter from the original kind of matter
chemical property
behavior that is related to the change of one kind of matter into another kind of matter
chemistry
study of the composition, properties, and interactions of matter
compound
pure substance that can be decomposed into two or more elements
cubic centimeter (cm3 or cc)
volume of a cube with an edge length of exactly 1 cm
cubic meter (m3)
SI unit of volume
density
ratio of mass to volume for a substance or object
dimensional analysis
(also, factor-label method) versatile mathematical approach that can be applied to computations ranging from simple unit conversions to more complex, multi-step calculations involving several different quantities
element
substance that is composed of a single type of atom; a substance that cannot be decomposed by a chemical change
exact number
number derived by counting or by definition
extensive property
property of a substance that depends on the amount of the substance
Fahrenheit
unit of temperature; water freezes at 32 °F and boils at 212 °F on this scale
gas
state in which matter has neither definite volume nor shape
heterogeneous mixture
combination of substances with a composition that varies from point to point
homogeneous mixture
(also, solution) combination of substances with a composition that is uniform throughout
hypothesis
tentative explanation of observations that acts as a guide for gathering and checking information
intensive property
property of a substance that is independent of the amount of the substance
kelvin (K)
SI unit of temperature; 273.15 K = 0 ºC
kilogram (kg)
standard SI unit of mass; 1 kg = approximately 2.2 pounds
law
statement that summarizes a vast number of experimental observations, and describes or predicts some aspect of the natural world
law of conservation of matter
when matter converts from one type to another or changes form, there is no detectable change in the total amount of matter present
length
measure of one dimension of an object
liquid
state of matter that has a definite volume but indefinite shape
liter (L)
(also, cubic decimeter) unit of volume; 1 L = 1,000 cm3
macroscopic domain
realm of everyday things that are large enough to sense directly by human sight and touch
mass
fundamental property indicating amount of matter
matter
anything that occupies space and has mass
meter (m)
standard metric and SI unit of length; 1 m = approximately 1.094 yards
microscopic domain
realm of things that are much too small to be sensed directly
milliliter (mL)
1/1,000 of a liter; equal to 1 cm3
mixture
matter that can be separated into its components by physical means
molecule
bonded collection of two or more atoms of the same or different elements
physical change
change in the state or properties of matter that does not involve a change in its chemical composition
physical property
characteristic of matter that is not associated with any change in its chemical composition
plasma
gaseous state of matter containing a large number of electrically charged atoms and/or molecules
precision
how closely a measurement matches the same measurement when repeated
pure substance
homogeneous substance that has a constant composition
rounding
procedure used to ensure that calculated results properly reflect the uncertainty in the measurements used in the calculation
scientific method
path of discovery that leads from question and observation to law or hypothesis to theory, combined with experimental verification of the hypothesis and any necessary modification of the theory
second (s)
SI unit of time
SI units (International System of Units)
standards fixed by international agreement in the International System of Units (Le Système International d’Unités)
significant figures
(also, significant digits) all of the measured digits in a determination, including the uncertain last digit
solid
state of matter that is rigid, has a definite shape, and has a fairly constant volume
symbolic domain
specialized language used to represent components of the macroscopic and microscopic domains, such as chemical symbols, chemical formulas, chemical equations, graphs, drawings, and calculations
theory
well-substantiated, comprehensive, testable explanation of a particular aspect of nature
uncertainty
estimate of amount by which measurement differs from true value
unit
standard of comparison for measurements
unit conversion factor
ratio of equivalent quantities expressed with different units; used to convert from one unit to a different unit
volume
amount of space occupied by an object
weight
force that gravity exerts on an object
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