3Matter Matter is everything that we see and many of the things we don’t see (as air). By definition matter has mass and occupies space.Matter is classified into two major categories:- Pure substances- MixturesBrass(mixture ofcopper & zinc)Pure silver
4MatterMatter can be changed. These changes may involve physical changes in which the composition of the matter is not changed or chemical changes in which the composition is changed.Candle burningIce melting
5Pure Substances Pure substances: - contain the same type of particles throughout.- have a definite composition.- may be either elements or compounds-sodium chlorideNaClsodiumNachlorineCl
8Elements & CompoundsAn element is a pure substance that cannot be broken into anther substance (by ordinary chemical means). Composed of only a single type of atom.A compound is a pure substance composed by two or more elementsHow about some examples?
9ElementsMany things are made of elements. For example, aluminum is used for foil and for building cars and trailers.Note: If its on the periodic table its an element!
12CompoundsCompounds are formed when two or more atoms of two or more elements combine chemically (bonding!).- fixed ratio of elements with a definite formula- separation into elements requires chemical proceduresWater H2ONote: Compounds are NOT on the periodic table.
15Mixtures Mixtures are materials made up of two or more pure substances.Mixtures can be separated by physical means based onphysical properties:evaporation filtrationfloating magnetsMixtures may be eitherhomogeneous (solutions)heterogeneous
17MixturesHomogeneous mixture of metal are “alloys”. Alloys include brass, steel, and white gold.Homogeneous mixtures in which one substance is dissolved in another is a “solution”. Solutions include coffee, IV fluids, and fog.
18Homogeneous Mixtures Examples: Sea water water and salt Coffee coffee, sugar, creamBlood red cells, white cells, plasmaAir nitrogen, oxygen, CO2Brass copper, zincWhite gold gold, silver, platinum
19Homogeneous Mixtures Corn flakes Brass Coffee jello Salt water colored Blood
25Physical & Chemical Properties Be sure to know the difference between:- Physical properties &chemical properties- Physical changes &chemical changes
26Physical PropertiesPhysical properties can be observed without a chemical reaction.Examples:color: water is clear, table salt is whitedensity: aluminum has a density of 2.7 g/cm3state: oxygen is a gas at room temperaturemagnetism: iron is attracted to magnettexture: gold is shiny
27Physical Properties What are some physical properties of: sulfur? lemonade?dish soap?
28Physical ChangesIn a physical change substances are not altered chemically, including:state changessolid liquidliquid gasmixing or separatingadding sugar to coffeeevaporating sea water for salttearing paper
29Physical Changes State Changes liquid solid “freezing” water to ice liquid gas “evaporation” water to steamgasoline to vaporsolid gas “sublimation” dry ice to CO2sublimationfreezingevaporation
30Physical Changes State Changes solid liquid “melting” ice to water ice cream meltinggas liquid “condensation” ice to watercondensationmelting
31Physical ChangesPhysical changes may involve changing shape but not composition;Breaking glassSawing woodPlaning wood
32Chemical Properties Chemical properties: The properties of an element or compound in a chemical reactionExamples:gasoline is flammablewater can be separated by electrolysisneon is inert
33Chemical changes Chemical reactions: - yield new substances - usually cannot be easily reversed- may either require or release energy (light, heat, etc.)Sugars in wood may be split by burning. Combustion yields new substances: CO2 and water and heat and light energy.