1. Chapter 5 Key Terms AnalysisAtoms ElementSymbols Diatomic MoleculeMolecular Formula Pure SubstancesMixtures Homogeneous MixtureSolution Heterogeneous MixtureColloids Tyndall EffectSuspension 1

2. Chapter 5 CLASSIFICATION OF MATTER 2

3. History  Greek Philosophers proposed that all matter was composed of 4 elements: earth, fire, water, air  1661, Robert Boyle published The Sceptical Chymist  Element is any substance that cannot be broken down into simpler substances  System for classifying matter  Elements  Compounds  Mixtures 3

4. Elements  Any substance that cannot be broken down into a simpler substance by ordinary chemical means  Elements are composed of only 1 type of atom  Atoms make up all elements  Symbols – used to represent names of elements  Consists of one or two letters derived from the element’s name  Oxygen = O  Hydrogen = H 4

5. Elements  First letter is capitalized, second letter is lowercase  Some symbols are derived from the element’s Latin name  Au  Ag  Na  Fe  MEMORIZE elements on page 92  Spelling and symbol 5

6. Elements  Most elements are solids at room temperature  Mercury and Bromine are liquids  Eleven are gases  Diatomic elements (molecule)  Elements that combine with itself to form 2 atom units  O 2, H 2  Most elements are naturally occurring, but some are only found in laboratories 6

7. Compounds  Substances with 2 or more different elements chemically bonded together  Water  Sugar  Molecules  Group of atoms held together by strong attractive forces  Smallest particle in a compound  Have all the same characteristics of the compound  A single molecule of water contains 2 H’s and 1 O 7

8. Compounds  Molecular formulas: tell us how many atoms of each element are in a molecule  Water – H 2 O  Baking Soda – NaHCO 3  Subscripts  Coefficients  2 H 2 SO 4  4 CaCO 3  Know the chemical formulas for the compounds on page 97 8

9. Compound or Element  Silver  Oxygen  Hydrogen peroxide  Iron  Sugar  Gold  Sulfuric acid  Sulfur 9

10. Mixtures  Consists of 2 or more pure substances (elements or compounds)  Ex. Sugar water (sugar and water)  The parts of a mixture keep their own properties  Sugar and water do not bond, they just mix  Separated by physical means  Parts of mixture can be in any proportion  Parts are physically combined, not chemically 10

11. Mixtures  Described by percent composition o 10 g of sugar and 90 g water – 10% sugar solution  Two types of mixtures  Homogeneous  Mixture that appears the same throughout  Ex. Air, stainless steel, 14-karat gold  AKA solution  Heterogeneous  Mixture has visibly different parts  Ex. Granite 11

12. Colloids Heterogeneous mixtures with small particles dispersed throughout which are hard to see Apparent via Tyndall Effect Pass a beam of light through solution See the beam in the solution = colloid No beam = a true solution Beam of light is dispersed by the particles in the colloid  Ex. Milk, Mayonnaise, lotions 12

13. Suspensions  Particles of a mixture will eventually settle out  Ex. Mud in water, snowglobes 13