ChemistryChemistry—The study of the properties of —The study of the properties of matter and how matter changes.matter and how matter changes.

ElementElement—a substance that cannot be —a substance that cannot be broken down into any other substances by broken down into any other substances by chemical or physical means. chemical or physical means.

Example: Carbon--CExample: Carbon--C All the matter around you is composed of All the matter around you is composed of

one element or a combination of two or one element or a combination of two or more elements.more elements.

Atoms—Smallest part of an element. All Atoms—Smallest part of an element. All atoms of an element have the same atoms of an element have the same chemical properties of atoms of other chemical properties of atoms of other elements.elements.

Molecule—a combination of two or more Molecule—a combination of two or more atoms. Some molecules are made of atoms. Some molecules are made of atoms that are alike, as is oxygen gas (Oatoms that are alike, as is oxygen gas (O22) ) that you breathe.that you breathe.

Compounds and MixturesCompounds and Mixtures CompoundsCompounds—A substance made of —A substance made of

two or more elements chemically two or more elements chemically combined. They have a chemical combined. They have a chemical formula.formula.

Examples: Sugar, SaltExamples: Sugar, Salt MixturesMixtures—Substances that are —Substances that are

mixed, butmixed, but NOT NOT chemically combined. chemically combined. They do not have formulas and can They do not have formulas and can be separated by physical means.be separated by physical means.

Examples: Dixie Cheeseburger, Iron Examples: Dixie Cheeseburger, Iron and Sandand Sand

Heterogenous mixture—mixture you Heterogenous mixture—mixture you can see the different parts can see the different parts

Example—lasagnaExample—lasagna Homogeneous mixture—mixture that Homogeneous mixture—mixture that

looks the same throughoutlooks the same throughout Example-milk, Crest toothpasteExample-milk, Crest toothpaste

ChangesChanges

Physical changesPhysical changes—A change that alters —A change that alters the form or appearance of a material, but it the form or appearance of a material, but it does not change the material into a new does not change the material into a new substance.substance.

All phase changes are physical.All phase changes are physical. Examples: tearing paper, evaporating water.Examples: tearing paper, evaporating water. Chemical changesChemical changes—A change in matter —A change in matter

that produces a new substance.that produces a new substance. Example: Burning woodExample: Burning wood

Signs of Chemical changes:Signs of Chemical changes:

Signs of a chemical change:Signs of a chemical change: A precipitate forms. (A solid that forms A precipitate forms. (A solid that forms

when two liquids are mixed.)when two liquids are mixed.) Color ChangeColor Change Gas Production (You should see Gas Production (You should see

bubbles.)bubbles.) Changes in temperatureChanges in temperature Changes in PropertiesChanges in Properties