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 Length, Mass, Volume, Density