Atmosphere—layers of air surrounding the Earth Atom—smallest particle into which an element can be divided and still have the properties of that element Compound—matter made up of two or more elements Comprise—contain something Element—substance that is made up of only one kind of matter Ocean—a large body of salt water Organisms—living things Atom—the smallest particle into which an element can be divided and still have the properties of that element Atomic mass—average mass of one atom of an element Atomic number—number of protons in the nucleus of one atom of an element; location on the periodic table Chemical formula—abbreviation that tells the elements and number of atoms in a molecule Chemical symbol—one- or two-letter code that stands for an element Compound—matter made of two or more elements Element—substance that is the building blocks of all matter; an element is made up of one kind of atom Molecule—smallest particle of a substance that still has the properties of that substance Periodic table of the Elements—a chart where all the elements are organized into periods and groups according to their properties Pure substance—a substance made up of only one kind of element Atom—the smallest particle into which an element can be divided and still have the properties of that element Chemical formula—abbreviation that tells the elements and number of atoms in a molecule Chemical symbol—one- or two-letter code that stands for an element Compound—matter made of two or more elements Element—substance that is the building blocks of all matter; an element is made up of one kind of atom Molecule—smallest particle of a substance that still has the properties of that substance Periodic table of the Elements—a chart where all the elements are organized into periods and groups according to their properties Pure substance—a substance made up of only one kind of element