acc chem unit 1

Physical Properties

Characteristics observed without changing the substance's identity. Can be measured or observed directly.

Physical Change

Alters appearance but NOT identity. No new substances formed; reversible in many cases

Chemical Properties

Characteristics that describe how a substance changes into a different substance.  Only observed when the substance undergoes a chemical reaction

Chemical Change

Creates new substances with different properties. Evidence: color change, gas production, temperature change, precipitate formation. Usually irreversible.

Elements

A substance that cannot be broken down into chemically simpler components

Atoms

The smallest part of an element that maintain the identity of that element.

Compounds

: A substances that can be broken down into chemically simpler components because it has more than one element.

Mixtures

A material composed of two or more substances where the individual substances maintain their chemical identities.

HETERogeneous mixtures

obvious combinations of two or more substances.

HOMOgenous mixtures

components are intimately combined that they act like a single substance.