Introduction to Chemistry

Chemistry

the study of matter and the changes that matter undergoes

properties and behaviour of matter

Matter

physical material of the universe; anything that has MASS and occupies SPACE

Atoms

the almost infinitesimally small BUILDING BLOCKS OF MATTER

Molecules

TWO OR MORE atoms are joined together in specific shapes

Property

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

relates to both the kinds of atoms the MATTER CONTAINS (composition) and to the ARRANGEMENTS of these atoms (structure).

States of Matter

CHANGES IN TEMP AND PRESSURE can lead to conversion from one state of matter to another, illustrated by such familiar processes as ice melting or water vapour condensing

Gas

NO FIXED VOLUME OR SHAPE; conforms to the volume and shape of container

compressed to occupy a smaller volume or expanded to occupy a larger one

Liquid

distinct volume independent of its container but no specific shape

ASSUMES THE SHAPE of the portion of its container.

Solid

DEFINITE SHAPE AND VOLUME

cannot be compressed to any appreciable extent.

Pure substance

has distinct properties and composition does not vary from sample to sample

Elements

118 elements with unique kind of atom

Compounds

composed of two or more elements

law of constant composition (law of definite proportions)

Elemental composition of a compound is always the same

Joseph Louis Proust

In 1790, this chemist discovered the Law of Definite Proportions.

Mixtures

combinations of two or more substances in which each substance retains its chemical identity

components

Substances making up a mixture

Heterogeneous Mixture

Different composition, properties, and appearance

Homogeneous/solution

uniform throughout

Physical Property

observed without changing the identity and composition of the substance

Chemical Property

describes the way a substance may change, or react, to form other substances

Intensive Property

does not depend on the amount of sample being examined; useful to identify substances

Extensive Property

relates to the amount of substance present

Physical Changes in Matter

change in physical appearance but not in composition

Chemical Changes in Matter

also called chemical reaction

a substance is transformed into a chemically different substance