Chapter 2 – Matter & Change Matter is anything that has mass and takes up space Mass is the amount of matter an object contains Volume is the amount of space an object occupies

Chapter 2 – Matter & Change Matter can exist in four states Solid Liquid Gas Plasma

Chapter 2 – Matter & Change Matter can be classified into two main groups Pure Substance Mixture A pure substance is a material with a definite composition and fixed properties Pure substances are divided into two groups Elements Compounds

Chapter 2 – Matter & Change An element is a pure substance with only one kind of atom All elements are found in the periodic table There are about 118 known elements Elements are represented with a chemical symbol Many symbols are based on the latin name Each symbol begins with an uppercase letter and subsequent letters are always lowercase

Chapter 2 – Matter & Change Compounds are two or more different elements chemically combined Compounds are represented with a chemical formula The formula tells what elements and how many atoms CO2 is one carbon atom and two oxygen atoms

Chapter 2 – Matter & Change Mixtures are a combination of two or more substances, where each substance maintains its identity The major difference between a mixture and a compound is that mixtures are easily separated There are two types of mixtures Homogeneous Heterogeneous

Chapter 2 – Matter & Change A homogeneous mixture is a mixture that looks the same (uniform) It has only one phase Homogeneous mixtures are also called solutions Solutions are composed of two parts Solute – is being dissolved Solvent – does the dissolving

Chapter 2 – Matter & Change Not all solutions are liquid Solid solution – gold jewelry Liquid solution – gasoline Gas solution – air

Chapter 2 – Matter & Change A heterogeneous mixture looks different (non uniform) Heterogeneous mixture may settle – orange juice

Chapter 2 – Matter & Change Determine whether the following is an element, compound, homogeneous mixture, or heterogeneous mixture Copper Rubbing Alcohol Granite Salt Carbon Dioxide Silicon Soda Sugar Concrete Helium Salad Dressing Air Stainless Steel Egg

Chapter 2 – Matter & Change Another way scientists classify matter is according to properties Properties are used to describe matter Properties can be either Intensive Extensive

Chapter 2 – Matter & Change An intensive property is independent on the amount of the sample For example, the density of aluminum is always 2.7 g/cm3 Regardless if the sample is large or small An extensive property is dependent on the amount of sample A large sample of aluminum will have a greater mass than a smaller sample

Chapter 2 – Matter & Change Properties can also be classified as Physical Chemical A physical property is a property that can be observed without changing the composition of the substance

Chapter 2 – Matter & Change A chemical property is a property that can only be observed when the composition of a substance changes

Chapter 2 – Matter & Change Identify the following as either physical or chemical properties Blue Color Density Flammability Melting Point Solubility Reacts with Acid to form H2 Supports Combustion Boiling Point Sour Taste Reacts with a Base to Form Water Hardness Luster Can Neutralize a Base Odor

Chapter 2 – Matter & Change Matter can also undergo changes Matter may change its appearance but not its composition That is a physical change Physical changes can be reversible or irreversible

Chapter 2 – Matter & Change Matter may change its appearance and its composition That is a chemical change Another name for a chemical change is a chemical reaction The starting materials in a chemical reaction are called reactants The ending materials in a chemical reaction are called products

Chapter 2 – Matter & Change Chemical changes are usually accompanied with four possible clues a transfer of energy a change in color the production of a gas the formation of a precipitate

Chapter 2 – Matter & Change Determine whether the following is a physical or chemical change. Sodium hydroxide dissolves in water. A pellet of sodium is sliced in two. Water is heated and changed to steam. Iron rusts. Evaporation. When placed in water, a sodium pellet catches on fire. Sugar dissolves in water. A tire is inflated with air. Pancakes cooking on a griddle. Food is digested in the stomach.

Chapter 2 – Matter & Change Regardless if the change is physical or chemical, the Law of Conservation of Mass is observed The Law of Conservation of Mass states that matter cannot be created or destroyed Therefore the initial amount of substance must equal the final amount of substance.