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MATTER: ELEMENTS AND COMPOUNDS It matters. It matters. • Anything that has a mass and a volume Close up view of atoms and their behavior Animated images are from http://www.chem.purdue.edu/gchelp/ • Changing from one state to another is a physical change • If a new substance is formed it is a chemical change Images are from http://www.chem4kids.com • The building blocks of Matter consist of Protons (+), Electrons (-), and Neutrons (N) Images are from http://www.chem4kids.com • Consist of only one kind of atom • Cannot be broken down into a simpler type of matter by either physical or chemical means without losing their identity • Can exist as either atoms or molecules • In the Earth’s crust, Oxygen is the most abundant element (46.6%) • Silicon is the second most abundant element (27.7%) • Aluminum (8.1%), Iron (5.0%), Calcium (3.6%), Sodium (2.8%), Potassium (2.6%), and Magnesium (2.1%) complete the list of elements that account for about 98.5% of the total mass of the earth’s crust • Aluminum, Iron, Oxygen, and Silicon make up about 88 percent of the earth's solid surface • Water on earth’s surface and in the air as clouds and fog are made of Hydrogen and Oxygen • The air is 99 percent Nitrogen and Oxygen • Hydrogen, Oxygen, and Carbon make up 97 percent of a person • Almost everything you see in this picture is made up of just six elements: Hydrogen, Oxygen, Carbon, Nitrogen, Aluminum, and Silicon • Atoms of two or more different elements chemically bound together Ex: H2O, NaCl, C6H12O6, CO2 • Can be broken down into elements again through a chemical reaction In the animation above, water (H2O) is a compound made of Hydrogen and Oxygen. Animated images and notes from http://www.chem.purdue.edu/gchelp/atoms/elements.html • The properties of the elements that make up a compound are often quite different from the properties of the compound itself • Sodium (Na) is a highly reactive metal • • Chlorine (Cl) is a poisonous gas Sodium Chloride (NaCl) is table salt • Compounds are made of molecules • A molecule is 2 or more atoms chemically bonded • Water = 2 atoms of Hydrogen and one atom of Oxygen = H2O • A molecule is the smallest particle of a compound that has all the properties of that compound • As all atoms of a certain element are alike, so are molecules of a certain compound alike • In the animation above, two nitrogen atoms (N + N = N2) make one Nitrogen molecule . • A shorthand way of representing compounds • If chemical symbols are the letters, these are the words • Ex: NH3 = ammonia C3H7OH = rubbing alcohol • Sometimes the formula represents a molecule of a single element • These are called diatomic molecules and this is how that element is naturally found • O2 = Oxygen H2 = Hydrogen Cl2 = Chlorine • Subscripts are small numbers used in chemical formulas • They are placed to the lower right of the chemical symbol • Subscripts represent # of atoms of an element in the compound • CO2 = 1 atom of Carbon and 2 atoms of Oxygen • H2SO4 = 2 atoms of Hydrogen, 1 atom of Sulfur and 4 atoms of Oxygen • Elements are pure substances that make up all matter on earth • The smallest piece of an element is an atom • Compounds are things made of a combination of elements • The smallest piece of a compound is a molecule • Atoms combine to form molecules