What is the difference between Elements , Compounds & Mixtures ?

1. What is the difference between Elements, Compounds & Mixtures? Unit 3 Structure and Organization of Matter

3. What ISN’T an Element? • Earth, wind, fire and water are NOT elements! • Earth - most all substances on the periodic table • Wind - air is made up of multiple gases • Fire - is plasma, anything burning • Water - Hydrogen & Oxygen

4. What ARE Elements? • Pure substances • Any substance with a single kind of particle • Those particles ALL have the same kind of atoms • The particles cannot be divided further. Diamond = pure carbon

5. How are Elements Identified? • Physical Properties • Boiling point • Melting point • Density • Chemical Properties • Reactivity with acid • Reactivity with oxygen

6. How are Elements Categorized? • By their properties • Physical & Chemical • Three major types of elements • Metals • Metalloids • Non-metals

7. Draw a table like the one below

8. What are Metals? • Shiny, good conductors of heat & electricity • Malleable - can bend • Ductile - pulled into wire • 95% of all elements are metals

9. The Metals

11. What are Non-metals? • Dull, not too shiny • Poor conductors of heat & electricity • Solids are brittle and break easily • Not many solid objects are made up of non-metals

12. The Non-metals

14. What are Metalloids? • They are semi-conductors • Some conduct electricity • Electrical conductivity is not as good as metals • Have some properties of both metals & nonmetals • Shiny, metallic appearance • Some are malleable & ductile

15. The Metalloids

18. What are Compounds? A pure substance made of 2 or more elements.

19. What else can be said of Compounds? • Elements combine through a chemical reaction • Elements don’t randomly form compounds • Elements combine in a very specific ratio - based on the element’s mass

20. What are the properties of Compounds? • Physical properties are similar to Elements: • Melting point, density, etc… • Chemical properties can include: • Reactivity to oxygen • Reactivity to acid • Reactivity to light Caffeine

21. Can Compounds be broken down? • Through a chemical change • Most time a lot of energy must be added to cause the change • Heat • Electricity • Light Light can break this compound down

22. What are common Compounds? • Common organic compounds include carbon, nitrogen, hydrogen and oxygen • Such as those found in caffeine • Theobromine - the active ingredient in chocolate

25. What is a Mixture? A combination of 2 or more substances that are NOT chemically combined

26. What is a Mixture? (continued) • Two or more substances will not react together • No chemical change occurs • Each substance has the same chemical makeup in the mixture • Salt water • The salt (NaCl) is still there as well as the water (H2O)

27. Can Mixtures be separated? • Yes, through…. • Distillation • Uses boiling points • Evaporation • Atmospheric pressure • Magnet • Removing iron • Centrifuge • Uses the densities

28. Made of elements, compounds, or both No charge in original properties of components - not electrical Separated by physical means Formed using ANY ratio of components Made of elements only Change in original properties of components Separated by chemical means Formed using a set ratio of components Mixtures vs. Compounds

29. What about the ratio of components in a Mixture? • Do not have to be mixed in any particular ratio • Granite is an excellent example of this quality to mixtures

30. What is a solution? • A mixture that appears to be a single substance • Composed of 2 or more substances that are distributed evenly among each other • Have the same appearance & properties throughout

31. What are parts to a solution? • The process of particles separating spreading through a mixture is called dissolving • Solute - the substance that is dissolved • Solvent - the substance in which thesolute isdissolved

32. What are examples of different Solutions? • Gas in gas - • dry air, O2 In N2 • Gas in liquid - • soft drinks, CO2 in H2O • Liquid in liquid - • antifreeze, alcohol in H2O • Solid in liquid - • Salt water, NaCl in H2O • Solid in solid (Alloy)- • brass, zinc in copper

33. What is Solubility? • The ability of a solute to dissolve in a solvent, like… • Putting sugar in water • Only so much sugar (solute) will dissolve in water (solvent)

34. What is the difference between Dilute & Concentrated • Dilute solution contains less solute • Concentrated solutions contain more solute

35. Dissolving gases in Liquids • As the solvent (water) becomes warmer the gas becomes less soluble • This is why a warm can of Mountain Dew will go “flat” faster. • Gas that is dissolved in the water can’t stay dissolved as the temperature rises.

36. On the other side, however…

37. Dissolving Solids in Liquids • Three ways to speed up the dissolving • Mixing/stirring (agitating) the solute in the solvent • Heating the solvent • Crushing the solute before placing it in the solvent 2 3 1

38. What is a Suspension? • A mixture in which the particles are dispersed throughout but are large enough to settle out • Heterogeneous • Must be shaken or stirred periodically to remain mixed • The suspension can be separated by use of a filter

39. Other Suspensions…

40. What are Colloids? • Mixtures with properties in between solutions & suspensions • Homogeneous • Particles are dispersed throughout but are not heavy enough to settle out

41. Other Colloids….

42. Our Atmosphere is a mixture

43. Element, Compound, or Mixture?

45. Next up ….. The Periodic Table of the Elements!