CHM1045 CH.1 Terms: Essential Ideas

Accuracy

How closely a measurement aligns with a correct value.

Atom

The 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

The study of the composition, properties, and interactions of matter.

Compound

Pure substance that can be chemically broken down into two or more elements.

Cubic centimeter

(cm^3 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

Pure substance that is composed of a single type of atom; a substance that cannot be broken down 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 °C,

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 cm^3.

Macroscopic domain

Domain 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; 1m = approximately 1.094 yards.

Microscopic domain

Domain of things that are much too small to be sensed directly.

Milliliter

(mL) 1/1,000 of a liter; equal to 1 cm^3 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

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

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

Domain of the specialized language used to represent components of the macroscopic and microscopic domains, such as chemical symbols, chemical formulas, chemical equations, graphs, drawings, and calculations.

Temperature

Intensive property representing the hotness or coldness of matter.

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.

Volume

Amount of space occupied by an object.

Weight

Force that gravity exerts on an object.

Physical property

Characteristic of matter that is not associated with any change in its chemical composition.

Unit conversion factor

Ratio of equivalent quantities expressed with different units; used to convert from one unit to a different unit.