a pure substance that cannot be separated or broken down into simpler substances by physical or chemical means
a substance in which there is only one type of particle; includes elements and compounds
elements that are shiny and are good conductors of thermal and electrical energy
elements that are dull and that are poor conductors of thermal and electrical energy
elements that have properties of both metals and nonmetals; semiconductors
a pure substance composed of two or more elements that are chemically combined.