Presentation on theme: "Dr. Childs Fall, 2005 Science Laboratory Matter and Changes in Matter."— Presentation transcript:
Dr. Childs Fall, 2005 Science Laboratory Matter and Changes in Matter
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 - Mixtures Pure silver Brass (mixture of copper & zinc)
Matter Matter 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. Ice melting Candle burning
Pure Substances Pure substances: - contain the same type of particles throughout. - have a definite composition. - may be either elements or compounds - sodium Na sodium chloride NaCl chlorine Cl
Types of Matter Matter Substance ElementCompound Mixture HomogeneousHeterogeneous
Elements & Compounds
An 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 elements How about some examples?
Many things are made of elements. For example, aluminum is used for foil and for building cars and trailers. Elements Note: If its on the periodic table its an element!
Elements Gold Lead Sulfur Oxygen Sodium lamp Hydrogen fuel
Compounds Compounds 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 procedures Water H 2 O Note: Compounds are NOT on the periodic table.
Compounds table salt NaCl table sugar C 6 H 12 O 6 Carbon dioxide CO 2 Nitrous oxide N 2 O rust Fe 2 O 3 Epsom salts MgSO 4 Sodium hydroxide NaOH
Mixtures are materials made up of two or more pure substances. Mixtures can be separated by physical means based on physical properties: evaporationfiltration floatingmagnets Mixtures may be either homogeneous (solutions) heterogeneous
Mixtures Homogeneous 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.
Examples: Sea water water and salt Coffeecoffee, sugar, cream Blood red cells, white cells, plasma Air nitrogen, oxygen, CO 2 Brasscopper, zinc White goldgold, silver, platinum Homogeneous Mixtures
Brass Coffee Blood colored water Corn flakes Salt water jello Homogeneous Mixtures
Examples: raisin bran cereal with raisins chocolate chip cookie tossed saladlettuce, tomatoes, carrots pizza pizza with meat, cheese granitefeldspar, mica Italian dressingoil, water, spice Heterogeneous Mixtures
Raisin Bran Granite Marble Muddy water Tossed salad Heterogeneous Mixtures Italian dressing Chocolate Chip cookie
Separating Mixtures evaporation salt ponds evaporation filtration distillation
Physical & Chemical Properties Be sure to know the difference between: - Physical properties & chemical properties - Physical changes & chemical changes
Physical Properties Physical properties can be observed without a chemical reaction. Examples: color: water is clear, table salt is white density: aluminum has a density of 2.7 g/cm 3 state: oxygen is a gas at room temperature magnetism: iron is attracted to magnet texture: gold is shiny
Physical Properties What are some physical properties of: sulfur? lemonade? dish soap?
Physical Changes In a physical change substances are not altered chemically, including: state changes solid liquid liquid gas mixing or separating adding sugar to coffee evaporating sea water for salt tearing paper
Physical Changes State Changes liquid solid“freezing” water to ice liquid gas “evaporation” water to steam gasoline to vapor solid gas“sublimation”dry ice to CO 2 freezing evaporation sublimation
Physical Changes State Changes solid liquid“melting” ice to water ice cream melting gas liquid “condensation” ice to water melting condensation
Physical Changes Planing wood Physical changes may involve changing shape but not composition; Sawing wood Breaking glass
Chemical Properties Chemical properties: The properties of an element or compound in a chemical reaction Examples: gasoline is flammable water can be separated by electrolysis neon is inert
Chemical 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: CO 2 and water and heat and light energy.