Classification of Matter

1. Classification of Matter

2. Every sample of matter can be classified as a: Pure Substance Mixture Homogeneous Solution Heterogeneous Colloid Suspension • Element • Molecule • Diatomic molecule • Compound

3. Pure Substances • Pure Substances cannot be broken down into any other substances by physical means Gold - element Manganese Dioxide - compound

4. Pure Substance • Element • composed of identical atoms • EX: copper wire, aluminum foil Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

5. Molecules • Groups of two or more atoms bound by chemical bonds • Can be two of the same element

6. Pure Substances Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

7. Sodium Chloride – NaCl (Table Salt) Sodium (Na) - Metal Chlorine (Cl) - gas Sodium Chloride NaCl Fixed ratio: 1 Na for every 1 Cl Sodium in water video

8. Pure Substances - FYI Law of Definite Composition • A given compound always contains the same, fixed ratio of elements. Two different compounds, each has a definite composition Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

9. Diatomic Elements, 1 and 7 H2 O2 F2 N2 Cl2 Br2 I2

10. Diatomic molecules are molecules composed only of two atoms, of the same elements. The prefix di- means two in Greek. Common diatomic molecules are hydrogen (H2), nitrogen (N2), oxygen (O2), Fluorine (F), Chlorine (Cl), Bromine (Br), and Iodine (I).

11. Chemical Formulas Shows the compound and the ratio of atoms

12. Mixtures Variable combination of two or more pure substances. Each keep individual properties Homogeneous- Evenly Mixed cannot see different parts. (Same) Heterogeneous – Can see different parts (different) Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

13. Tyndall Effect • The scattering of light by particles in a mixture • http://www.youtube.com/watch?v=gheuYqQ6phE&feature=related

14. Mixtures Solution • homogeneous • very small particles • no Tyndall effect • particles don’t settle • Examples: • rubbing alcohol (ethyl alcohol and water) • Air (nitrogen and oxygen)

15. Mixtures Colloid • heterogeneous • medium-sized particles • Tyndall effect • particles don’t settle • Particles scatter light • EX: • Milk • Clouds • Smoke • mayo Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

16. Mixtures Suspension • heterogeneous • large particles • Tyndall effect • particles settle • EX: • fresh-squeezed lemonade • Sand in water Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

17. MATTER yes no Can it be physically separated? MIXTURE PURE SUBSTANCE yes no yes no Is the composition uniform? Can it be chemically decomposed? Homogeneous Mixture (solution) Heterogeneous Mixture Compound Element Colloids Suspensions Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

18. Elements, Compounds, and Mixtures Consider Concentration Here! oxygen atoms hydrogen atoms hydrogen atoms (b) a compound (water) (c) a mixture (hydrogen and oxygen) (d) a mixture (hydrogen and oxygen) (a) an element (hydrogen) Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 68

19. Both elements and compounds have a definite makeup and definite properties. Mixtures two or more substances that are physically mixed Compounds two or more kinds of atoms that are chemically bonded Elements only one kind of atom; atoms are bonded if the element is diatomic or polyatomic substance with definite makeup and properties

20. Classification of Matter hetero- geneous mixture no uniform properties? no solution fixed composition? no element chemically decomposable? yes compound http://antoine.frostburg.edu/chem/senese/101/matter/slides/sld003.htm

21. Compounds vs. Mixtures • Compounds have properties that are uniquely different from the elements from which they are made. • A formula can always be written for a compound • e.g. NaCl  Na + Cl2 • Mixtures retain their individual properties. • e.g. Salt water is salty and wet

22. Classification of Matter MATTER (gas. Liquid, solid, plasma) Separated by PURE SUBSTANCES MIXTURES physical means into Separated by COMPOUNDS ELEMENTS HOMOGENEOUS MIXTURES HETEROGENEOUS MIXTURE chemical means into Kotz & Treichel, Chemistry & Chemical Reactivity, 3rd Edition , 1996, page 31

23. Classification of Matter Matter Physically separable Substance Definite composition (homogeneous) Mixture of Substances Variable composition Chemically separable Element (Examples: iron, sulfur, carbon, hydrogen, oxygen, silver) Compound (Examples: water. iron (II) sulfide, methane, Aluminum silicate) Homogeneous mixture Uniform throughout, also called a solution (Examples: air, tap water, gold alloy) Heterogeneous mixture Nonuniform distinct phases (Examples: soup, concrete, granite)

24. Mixture vs. Compound Alike Different Different Involve substances Variable Composition Fixed Composition Topic Topic No bonds between components Contain two or more elements Bonds between components Mixture Compound Can be separated by physical means Can be separated into elements Can ONLY be separated by chemical means

25. Top TenElements in the Universe Percent Element (by atoms) • Hydrogen 73.9 • Helium 24.0 • Oxygen 1.1 • Carbon 0.46 • Neon 0.13 • Iron 0.11 • Nitrogen 0.097 • Silicon 0.065 • Magnesium 0.058 • Sulfur 0.044 A typical spiral galaxy (Milky Way is a spiral galaxy) Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 26

26. The Composition of Air Nitrogen Helium Oxygen Air Neon Water vapor Carbon dioxide Argon Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 34

27. Chart Examining Some Components of Air Nitrogen consists of molecules consisting of two atoms of nitrogen: Oxygen consists of molecules consisting of two atoms of oxygen: Water consists of molecules consisting of two hydrogen atoms and one oxygen atom: Argon consists of individual argon atoms: Carbon dioxide consists of molecules consisting of two oxygen atoms and one carbon atom: Neon consists of individual neon atoms: Helium consists of individual helium atoms: N2 O2 H2O Ar CO2 Ne He Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 35

28. Matter Flowchart Examples: • graphite • pepper • sugar (sucrose) • paint • soda element hetero. mixture compound hetero. mixture solution homo. mixture Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

29. Mixtures Examples: • mayonnaise • muddy water • fog • saltwater • Italian salad dressing colloid suspension colloid solution suspension Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

30. Reviewing ConceptsClassifying Matter • Why does every sample of a given substance have the same properties? • Explain why the composition of an element is fixed. • Describe the composition of a compound. • Why can the properties of a mixture vary? • On what basis can mixtures be classified as solutions, suspensions, or colloids?

31. Separating a Mixture

32. Separating a Mixture • Chromatography - To separate different colored dyes. The dyes travel up the chromatography paper at different distances before they cannot remain in solution. The more soluble dyes move further up than the less soluble ones, hence separating from each other.

33. Separating a Mixture • Distillation - to separate and collect a liquid from a solution of a soluble solid. The solution is heated in a flask until the liquid boils. The vapor produced passes into the condenser where it is cooled and condenses to a liquid. The pure liquid (distillate) is collected in a beaker.

34. Separating a Mixture Evaporation – This method is suitable to separate a soluble solid from a liquid. If the solution is heated, the liquid evaporates leaving the solid behind.

35. Separating a Mixture Fractional Distillation - This is a special type of distillation used to separate a mixture of liquids. Different liquids boil at different temperatures. When heated, they boil off and condense at different times. The apparatus features a fractionating column, which ensures that only the liquid boils at its boiling point will pass into the condenser.

36. Separating a Mixture Filtration – To separate an insoluble solid from a liquid. The solid remains in the filter paper and the liquid goes through the paper into the beaker.