Classifying Mixtures A mixture is a physical blend of two or more substances. Two Types: Heterogeneous Homogeneous Heterogeneous: not uniform in composition (ex. a salad) Homogeneous: completely uniform in composition (ex. salt water) homogeneous mixtures are called solutions Solutions: have the same composition throughout and can be gases, liquids, or solids. Any part of a system with uniform composition and properties is called a phase Types of Solutions Liquid-Gas Liquid-Liquid Solid-Liquid Solid-Solid Gas-Gas Gas-Liquid

Elements & Compounds Elements: smallest form of matter that can exist under normal laboratory conditions, elements cannot be separated into simpler substances~ Building Blocks Compounds: Two or more elements combine with one another to form compounds. Compounds are substances that can be separated into simpler substances only by chemical means. (Ex. if you burn sugar, it eventually turns black, breaking down into carbon and water vapor. Water can still be broken down, so it is a compound. Carbon cannot, so it is an element.)

Fermentation of Sugar Gay Lussac discovered the general chemical equation for the breakdown of sugar into ethanol and carbon dioxide: C6H12O6---- 2CH3CH2OH + 2CO2

Chemical Symbol Chemical Symbol: each element is represented by a one or two letter chemical symbol Examples: C, N, O, H, Na, Cl, F, Mg, S

Review Which of the following are Homogeneous? Heterogeneous? (a) spaghetti sauce (b) glass (c) muddy water (d) cough syrup (e) mixture of nitrogen gas and helium gas Hetero Homo

Review Name the type of solution (a) Sodium Chloride in water (brine) Types of Solutions Liquid-Gas Liquid-Liquid Solid-Liquid Solid-Solid Name the type of solution (a) Sodium Chloride in water (brine) (b) Copper in Silver (sterling silver alloy) (c) Water vapor in air (moist air) (d) Acetic acid in water (vinegar) Answers a. Solid-Liquid b. Solid-Solid c. Liquid-Gas d. Liquid-Liquid

Review What would be an example of a Gas-Gas solution? What would be an example of a Gas-Liquid solution? Carbon dioxide and oxygen in nitrogen (air) Carbon dioxide in water

Review Classify each of the following as a substance or a mixture (a) silver (b) alphabet soup (c) textbook (d) table salt (NaCl) (a) substance (b) mixture (c) mixture (d) substance

Review How do you distinguish between an element and a compound? Compounds can be separated by physical means into elements; elements cannot be separated into simpler substances by chemical techniques Compounds can be separated by chemical means into elements; elements cannot be separated into simpler substances by chemical techniques Compounds can be separated by physical means into elements; elements can be separated into simpler substances by chemical techniques Compounds can be separated by chemical means into elements; elements can be separated into simpler substances by chemical techniques

Review What is the chemical symbol for each of the following elements? Copper C Cu Co Cd Phosphorus Pb Sn P Po Silver S Se Sn Ag Sodium Sb Na

Review Name the chemical elements represented by the following symbols Sn Lead Tin Sulfur Ca Cadmium Calcium Chlorine S Sulfur Tin Selenium