•Matter is anything that has mass and takes up space.
–Ex: Your textbook, you, your pen/pencil, air, etc.
•Classification systems are used all the time to organize objects. –Ex: The Periodic Table of Elements, organizing your locker, your clothes, etc. •In order to make the study of matter easier to understand, scientists have developed ways to classify matter. •The properties of materials can be used to classify them into general categories. –Ex: Pure substances, elements, compounds, mixtures, etc. •Materials are made of a pure substance or a mixture of substances. –Substance: A type of matter with a fixed composition.
•A substance can either be an element or a compound.
–Ex: Helium, Aluminum, Water, Salt, etc.
•Elements are built from atoms.
–Atom: The smallest particle of an element that still retains the properties of the element. –Element: Simplest type of pure substance.
•Elements cannot be changed into simpler substances by any physical or chemical means. •About 90 elements are found on Earth, and more than 20 others have been made in the laboratory (radioactive). –Ex: Iron (Fe), Carbon (C), Oxygen (O), Gold (Au), Uranium (U), etc. •Each element is designated by a one or two letter symbol that is used worldwide. •Symbols for the elements are always a single capital letter or a capital letter followed by a lowercase letter. •Chemical symbols are just a shorthand way of representing the elements. •Some of the symbols are from the Latin or German names.
–Ex: Tungsten (W = Wolfram), Sodium (Na = Nadium), Gold (Au = Aurum), Potassium (K = Kalium), Lead (Pb = Plumbum), etc. •Each of the more than 110 elements that we know of is unique and has different properties from the rest.
•Compounds are pure substances made of atoms of two or more different elements that are chemically combined. –Ex: Water (Hydrogen and Oxygen), Nylon (Carbon, Hydrogen, Nitrogen, and Oxygen), Table Salt (Sodium and Chlorine), etc. •Every compound is different from the elements it contains. –Ex: Water – made of two gases (hydrogen and oxygen).
–Ex: Salt – made of a metal (sodium) and a gas (chlorine). •When elements combine to make a specific compound, the elements combine in the same proportions. –Ex: Iron Oxide (rust) always has two atoms of iron for every three atoms of oxygen. •Compounds can be broken down into simpler substances.
–Ex: Sugar = By heating sugar you can separate it into carbon and water vapor. •Most compounds are made of molecules.
–Molecules: Made of two or more atoms chemically bonded together. •A molecule is the smallest particle of a compound that has all the properties of that compound. •All molecules of a compound are alike.
•A molecule may consist of two or more atoms of different elements or atoms of the same element. –Ex: Water molecule = H2O, Oxygen molecule = O2, Phosphorus molecule = P4, Sulfur molecule = S8, Ozone molecule = O3, Sugar molecule = C6H12O6, Carbon Dioxide molecule = CO2, etc. •A chemical formula shows how many atoms of each element are in a unit of a substance. •In a chemical formula, the number of atoms of each element is written after the elements symbol as a subscript. •If only one atom is present, no subscript number is used. –Ex: Water = H2O, Table Salt = NaCl, Sugar = C6H12O6, Indigo = C16H10N2O2, Octane = C8H18, Hydrogen Peroxide = H2O2, etc. •A mixture is a combination of two or more substances that are not chemically bonded. –Ex: Grape juice – the composition is not fixed; it can have different amounts of water or sugar. • Elements and compounds are pure substances, but mixtures are not. •Mixtures are formed by mixing pure substances.
•A mixture can be separated into its components.
–Ex: The components of water, a pure substance, are chemically combined and cannot be separated in the same way that the components of grape juice can be separated. 3 Properties of Mixtures:
–Substances keep their own separate...