Physical Properties and Physical Changes l A physical

Physical Properties and Physical Changes

l. A physical property is a characteristic that can be observed or measured without changing the identity of the substance. – Melting and boiling point

l. A change in a substance that does not involve a change in the identity of the substance is a physical change – Cutting, boiling grinding, melting, and

Changes of State

l. A change of state is a physical change of a substance from one state to another.

– Matter in the solid state has definite volume and definite shape. – Matter in the liquid state has definite volume but an indefinite shape.

– Matter in the gas state has neither definite volume nor definite shape. – Plasma is a high-temperature physical state of matter in which atoms lose their electrons.

Chemical Properties and Chemical Changes

l. A chemical property relates to a substance’s ability to undergo changes that transform it into different substances. – Burning, rusting, tarnishing

l. A change in which one or more substances are converted into different substances is called a chemical change (chemical reaction).

l reactants l products l Chemical changes DO NOT affect the total amount of matter present before and after a reaction.

How do you know if a chemical change has occurred? 1. 2. 3. 4. Color change Temperature change Production of a gas (bubbles) Precipitate forms

What is a precipitate? A precipitate forms when two clear solutions are combined and a solid substance settles out, the solid is insoluble and is called the precipitate Sometimes the solution will just look cloudy.

Energy and Changes in Matter l When physical or chemical changes occur, energy is always involved l Energy can be absorbed (endothermic) endothermic or released (exothermic), exothermic but is not created or destroyed. l What law is this?

Phase Changes l l Energy Absorbing – Melting – Boiling – Sublimation Energy Releasing – Freezing – Condensation – Deposition