Physical and Chemical Changes

Properties of Matter•All pure substances have

characteristic properties

•Properties are used to distinguish between substances

•Properties are also used to separate substances

Physical Properties

•A Physical Property is a characteristic that can be observed or measured without changing the composition of the substance

•Physical properties describe the substance itself

•Examples▫Changes of State▫Color▫Mass, shape, length▫Magnetic properties

States of Matter•There are three common states of matter: solid, liquid, and gas

Solids•Definite shape and definite volume•Particles are packed tightly together and held in fixed positions

•Particles vibrate about fixed points

Liquids•Definite volume•Takes the shape of its container

▫Example: Milk in a glass vs. Milk in a gallon jug

•Particles can move past each other (fluid)▫Fluid – Anything that can be poured

•Particles move more rapidly than in a solid

Gases•No definite shape, takes the shape of

its container•No definite volume•Particles are spread far apart and move

past each other rapidly

Chemical Properties•A Chemical Property

indicates how a substance will react with another

•Chemical properties cannot be determined without changing the identity of the substance

•Examples:▫Iron Rusting▫Silver Tarnishing

Physical Changes•A Physical Change is a change in a

substance that does not alter the substance’s identity▫Examples:

Grinding Cutting Melting Boiling

Chemical Changes•A change in which one or more

substances are converted into different substances is called a Chemical Change

•Signs of a Chemical Change:▫Color Change▫Gas is Released▫Temperature Change▫Precipitate – Solid falls out of solution▫Substance Disappears

Intensive vs. Extensive Properties•Extensive properties depend on

the amount of matter that is present▫Examples: Energy in a substance,

Volume, Mass

• Intensive properties do not depend on the amount of matter present▫Examples: Density, Melting Point,

Boiling Point

Qualitative vs. Quantitative Measurements

•Qualitative measurements are descriptive▫Examples:

Physical State, Color, Shape, Sound, Smell

•Quantitative measurements are numerical▫Examples:

Length, Mass, Volume, Density