Chemistry Notes

1. Chemistry Notes 6th Grade Science 2010-2011 Unit 1

2. Elements, Compounds, and Mixtures What Do You Think? How is an element different from a compound? Unit 1

3. Answer An element is made up of only one pure substance, and a compound is composed of two or more elements that are chemically combined. Gold http://www.worldofrockhounds.com/huge-gold-nugget-sm.JPG Water http://www.nbmg.unr.edu/slides/water/5.htm Unit 1

4. Elements An element is a pure substance that cannot be separated into simpler substances by physical or chemical means. Unit 1

5. Elements A pure substance is a substance in which every particle of that element is the same. • Example: Every particle in a 5g gold nugget is like every other particle of gold, no matter where they are found. http://www.libertarian.nl/NL/archives/01-gold-bar.jpg Unit 1

6. Elements Every element has a unique set of properties. The Periodic Table of Elements is arranged according to these properties. Unit 1

7. Elements Every element has a unique set of properties. Some physical properties that are used to classify elements are boiling point, melting point, color, and density. Unit 1

8. Elements Chemical properties used to separate elements from each other include reactivity with acids, or reactivity with oxygen. Unit 1

9. Elements Are Grouped Some elements are shiny, and can conduct thermal energy. They are all grouped together on the left hand side of the Periodic Table. They are called metals. Not all metals are exactly alike, but they do have some properties in common. Unit 1

10. Elements Elements Can Be Identified By Categories If you know the category, you know the properties. 1. Share with your class how CDs can be classified by categories? 2. How can dogs be classified by categories? Try this! Unit 1

11. Elements are identified by 3 main categories Metals Nonmetals Metalloids Elements Unit 1

12. Elements Metals Metals are elements that are usually shiny and good conductors of electricity and heat. Unit 1

13. Elements Metals Metals are also malleable (can be hammered into thin sheets). Unit 1

14. Elements • Metals are ductile, or can be drawn into thin wires. • Metals are located to the left of the “zig zag line” on the Periodic Table. Unit 1

15. Elements • Examples: Iron (Fe) and Copper (Cu). http://www.flamo.net/crystals/iron.jpg http://resourcescommittee.house.gov/subcommittees/emr/usgsweb/materials/copper.html Unit 1

16. Elements Click below to see properties of Metals. http://www5.unitedstreaming.com/index.cfm Unit 1

17. Elements Nonmetals • Usually dull and poor conductors of heat and electric current. • Tend to be brittle and unmalleable. Unit 1

18. Elements Nonmetals • Nonmetals are located to the right of the “zig zag line” on the Periodic Table. Unit 1

19. Elements Nonmetals • Examples: Neon (Ne) and Carbon (C) www.neonstreet.com/ sign2.html reluctant-messenger.com/ diamond_sutra.htm Unit 1

20. Elements Click below to see properties of Nonmetals http://www5.unitedstreaming.com/index.cfm Unit 1

21. Elements Metalloids Share properties of both metals and nonmetals. • Can be shiny or dull. • Somewhat malleable and ductile. Unit 1

22. Elements • Metalloids touch the “zig zag line” on the Periodic Table. • Examples: Silicon (Si) Arsenic (As). Unit 1

23. Elements Click below to see properties of metalloids. http://www5.unitedstreaming.com/index.cfm Unit 1

24. Let’s Review! - 1 - Describe some physical properties of the element iron. http://neil.fraser.name/news/2004/05/22/ Unit 1

25. Answer Physical properties include: • Melting Point: 1535 °C • Density: 7.9 g/cm3 • Iron has the ability to conduct heat and electrical current. Unit 1

26. Let’s Review - 2 - What is an example of a metal that is very malleable, shiny, and is used often in kitchens? Unit 1

27. Answer Aluminum Foil Unit 1

28. Compounds What Do You Think? What do salt, sugar, baking soda, and water have in common? Unit 1

29. Compounds A compound is a pure substance composed of two or more elements that are chemically combined. Unit 1

30. Compounds Properties of Compounds • Compounds, like elements, can be identified by their own physical and chemical properties. • What are some examples of physical and chemical properties? Unit 1

31. Compounds Each compound has differentproperties than the elements that make them up. Unit 1

32. Compounds Compounds are Composed of Elements. The compound Water is composed of Hydrogen and Oxygen chemically bonded together. Unit 1

33. Compounds Compounds are Composed of Elements. • The compound Ammonium is composed of Nitrogen and Hydrogen chemically bonded together. Unit 1

34. Compounds Click below to see a video clip of sodium metal and chlorine gas being combined. Unit 1

35. Let’s Review! - 1 - What is the difference between an element and a compound? Unit 1

36. Answer • An element is a pure substance that cannot be separated into simpler means by physical or chemical means. • A compound is a pure substance composed of two or more elements that can be broken into simpler substances by a chemical change. Unit 1

37. Compounds Make a Venn diagram comparing and contrasting elements and compounds. Activity for Chapter 2 Elements Compounds Unit 1

38. Elements, Compounds, and Mixtures Pre-AP Extensions for Chapter 2 • Mixtures are combinations of two or more elements that are not chemically combined. • Mixtures can be separated into 2 types: homogenous mixtures and heterogenous mixtures. Unit 1

39. Elements, Compounds, and Mixtures Homogenous Mixtures • A homogenous mixture is a mixture of two or more substances that is completely uniform in composition. • Homogenous mixtures can be separated by physical means, but it is often difficult to do. • Examples include salt water, kool aid, and air. Unit 1

40. Elements, Compounds, and Mixtures Heterogenous Mixtures • A heterogenous mixture consists of many different items, which are often not easily sorted or separated, though they are clearly distinct. • Examples include oil and water mixed together, sand or gravel, and even chocolate chip cookies! Unit 1

41. Elements, Compounds, and Mixtures Websites to Visit • Percent Calculations in a Mixture • Chromatography Mixtures Lab Unit 1

42. Introduction to the Periodic Table What Do You Think? How do scientists use physical properties to arrange elements on the periodic table? Unit 1

43. Introduction to the Periodic Table Dimitri Mendeleev discovered a pattern to the elements in the periodic table in 1869. www.astrosurf.org/lombry/ quantique-histoire.htm Unit 1

44. Introduction to the Periodic Table He simply wrote the names of all of the elements on cards, along with some of their properties. Unit 1

45. Introduction to the Periodic Table • Mendeleev tried arranging his cards based on different properties like color, density, melting point, and atomic mass. • He found that by arranging the elements by increasing atomic mass, he found many other properties that fit a pattern. Unit 1

46. Introduction to the Periodic Table Mendeleev found that by arranging the elements by increasing atomic mass, similar physical and chemical properties repeated in every 8th element. This is called periodic, or having a regular, repeating pattern. Can you think of anything else that is periodic? Unit 1

47. Let’s Review! - 1 - Why was Mendeleev so important in the study of the periodic table? Unit 1

48. Answer • Mendeleev was responsible for arranging the periodic table by increasing atomic mass. • This arrangement organizes the table making it easier for us to use. Unit 1

49. Introduction to the Periodic Table What Do You Think? How do scientists use physical properties to arrange elements on the periodic table? Unit 1

50. Introduction to the Periodic Table Elements are classified on the periodic table based on their properties. • Like we learned in Chapter 2, we classify them as metals, nonmetals, and metalloids. Unit 1