Matter Notes: Properties (Part 2) WCHS Chemistry

Physical and Chemical Changes

Physical Change Occurs when substances do not change their chemical identities! Substances are not altered chemically No new products are formed Physical changes can usually be reversed! Ex: dissolving, state changes,

Chemical Change Occurs when a substance changes into/ becomes a different substance. Chemical changes happen on a molecular level *******Chemical changes are NOT reversible!

Evidence of Chemical Changes A gas is produced (Ex: bubbles) The temperature changes → by itself! A substance disappears A solid is formed A color change occurs A new odor is produced.

Chemical & Physical Properties = Characteristics used to describe objects

Physical Property Can be measured without changing the chemical composition of a substance Ex: color, odor, shape, size, boiling, and freezing point.

Chemical Property Describes a substance’s “potential” to undergo some chemical change Ex: reactivity with water, pH, flammability.

Intensive & Extensive Properties

Intensive Property Does NOT depend on the system size of the amount of material involved. Ex: density, temperature, color, melting and boiling point.

Extensive Property Does depend on the system size or the amount of material in the system. Ex: Mass, volume, length