Properties and Changes in Matter

Properties of matter

Physical Properties Can be observed or viewed without changing the sample’s composition Example: density, color, odor, state of matter, boiling point, melting point, shape Use your senses

Properties Extensive Intensive Properties that depend on the amount of substance present Example: Volume, mass Properties that are independent of the amount of substance present Can be used to identify a substance Example: density, boiling point, temperature

Chemical Properties How a substance interacts with another substance (ability or inability) Example: iron can react with oxygen, carbon dioxide is not flammable

Changes in matter

Physical Changes Alter a substance without changing the composition Example: bend, grind, crumple, split, phase change

Chemical Changes Process in which a substance(s) is changed into one or more new substances Example: combust, ferment, burn, rot, tarnish Also known as a chemical reaction

Chemical Equation Use of symbols to represent a chemical reaction Example: CH4 + O2 → CO2 + H2O

Reactants Products Starting substances Found on the left hand side of a chemical equation Substances formed Found on the right hand side of a chemical equation Have students identify reactants and products

Law of Conservation of Mass Mass is neither created or destroyed during a chemical reaction Mass of the reactants = mass of the products

Chemical Reaction Signs Bubbling (gas production) Color change Precipitate forms (solid formation) Energy change (temperature change) The only way to know for sure is to check the composition before and after!!