Lecture 1- CHEMISTRY THE CENTRAL SCIENCE 1

Chemistry

The branch of science that studies the properties, composition, and behavior of matter.

Matter

Anything that has mass and occupies space.

Substance

A form of matter that has a definite (constant) composition and distinct properties.

Mixture

A combination of two or more substances in which the substances retain their distinct identities.

Element

A substance that cannot be separated into simpler substances by chemical means.

Compound

A substance composed of atoms of two or more elements chemically united in fixed proportions.

Homogeneous mixture

A mixture with a uniform composition throughout.

Heterogeneous mixture

A mixture where the composition is not uniform.

Physical properties

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

Chemical properties

Properties that can be observed when the matter undergoes a chemical change.

Intensive properties

Properties that do not depend on the amount of matter in a sample.

Extensive properties

Properties that depend on how much matter a sample contains.

SI Base Units

International System of Units used for measurement.

Density

The mass per unit volume of a substance.

Significant Figures

Digits in a number that carry meaningful information about its precision.

Precision

How close a set of measurements are to each other.

Accuracy

How close a measurement is to the true value.

Temperature

A measure of the average kinetic energy of the particles in a substance.

Scientific Method

A systematic approach to acquiring knowledge through observation, hypothesis, experimentation, and theory.