Chemistry: The Central Science Chapter 1

Matter

Anything that has mass and occupies space.

Property

Any characteristic that allows us to recognize a particular type of matter and to distinguish it from other types.

Molecules

Two or more atoms that are joined together in specific shapes.

Gas

Has no fixed volume or shape; conforms to the volume and shape of its container.

Liquid

Has a distinct volume independent of its container but has no specific shape. Cannot be compressed.

Solid

Has both a definite shape and a definite volume. Cannot be compressed.

Pure Substance

Matter that has distinct properties and a composition that does not vary from sample to sample.

Ex. Water and Table Salt.

Elements

Substances which cannot be decomposed into simpler substances. On a molecular, each is composed of only one kind of atom.

118 are known.

Compounds

Substances composed of two or more elements; they contain two or more kinds of atoms. Composition is fixed.

Ex. Water (H₂0)

Mixture

Combinations of two or more substances in which each substance retains its chemical identity. Composition can vary.

Physical Properties

Properties that can be observed without changing the identity and composition of the substance.

Ex: color, odor, density, melting point, boiling point, hardness.

Chemical Properties

Properties which describe the way a substance may change, or *react* to form other substances.

Ex: flammability

Intensive Properties

Properties that do not depend on the amount of sample being examined and are particularly useful in chemistry because many intensive properties can be used to *identify* substances.

Extensive Properties

Properties that depend on the amount of sample. They relate to the amount of substance present.

Ex: Mass and Volume.

Physical Change

A change in the physical appearance but not the composition of the substance. It remains the same substance before and after the change.

Ex: The Evaporation of water.

Chemical Change/Chemical Reaction

A change in which a substance is transformed into a chemically different substance.

Ex: when Hydrogen burns in air, it combines with oxygen to form H₂0

SI Prefix: Giga

SI Meaning: 10⁹

SI Prefix: Mega

SI Meaning: 10⁶

SI Prefix: Kilo

SI Meaning: 10³

SI Prefix: Deci

SI Meaning: 10⁻¹

SI Prefix: Centi

SI Meaning: 10⁻²

SI Prefix: Milli

SI Meaning: 10⁻³

SI Prefix: Micro

SI Meaning: 10⁻⁶

SI Prefix: Nano

SI Meaning: 10⁻⁹

Mass

The measure of the amount of material in an object.

Volume x Density

Temperature

A measure of the hotness or coldness of an object. A physical property that determines the direction of heat flow. Heat always flows spontaneously from a substance at a higher temperature to one at a lower temperature.

Kelvin to Celsius

K= °C + 273.15

Fahrenheit to Celsius

°F = 9/5 (°C) + 32

Celsius to Fahrenheit

°C = 5/9 (°F - 32)

Volume

(length)³
Mass/ Density

Speed

m/s

Density

Mass / Volume

Exact Numbers

A quantity that doesn't need measure.

Ex: Number of people in Chemistry class

Inexact Numbers

If the number has been measured.

Ex: Mass of a penny

Precision

A measure of how closely individual measurements agree with one another.

Accuracy

Refers to how closely individual measurements agree with the correct value.

Significant Figures

The numbers of a measurement that are reasonable to report.

All digits of measured quantity, including the uncertain one.