1. Topic: Chemistry Aim: Explain how elements are classified in the Periodic Table of Elements. Do Now: How do you find out the number of neutrons in an atom? HW: complete periodic table handout

3. Periodic Table of Elements System pf grouping all of the known elements and to predict the properties of elements

4. Element Key

5. Atomic number: # of protons –Never changes –# of electrons –Different for each element

6. Element Key

7. Atomic mass: average mass of atoms ins an element Mass number: protons + neutrons –Round up the atomic mass

9. How can we determine the # of neutrons? Mass # - Atomic #

10. How many protons? How many electrons? How many neutrons? 2 2 4-2 = 2

13. How are elements arranged? In order of increasing atomic number

14. Columns Groups or Families Elements have similar BUT NOT identical properties

15. Ex: Family 1: –are all soft, white, shiny metals –highly reactive

16. Rows Periods (7 of them) Elements are not alike in properties Left to right  atomic # increases

17. 1st element  extremely active solid Last element  inactive gas

18. 4 main categories of PT Metals, Nonmetals, Metalloids, Noble Gases

19. 1. Metals: 88 elements to left of zigzag line (metals or metal-like elements)

21. Physical Properties of Metals : –Luster (shininess) –Ductile (can be pulled into wires) –Malleable (can be beaten into sheets)

22. –Good conductors (allow heat and electricity to move through easily)

23. High density and melting point

24. Chemical Properties of Metals –Corrosive (gradual wearing away due to chemical reaction) Rusting of iron (combines with O2 in air to form iron oxide) Tarnishing of silver (combines with sulfur in air)

25. 2. Nonmetals: to right of zigzag line

26. Physical Properties of Nonmetals –No luster (dull) –Not good conductors of heat and electricity

27. –Brittle (break easily) –Not ductile or malleable –Lower densities and melting points

28. Sulfur

29. 3. Metalloids: have properties of both metals and nonmetals

30. Physical properties: –Shiny or dull –Semi-conductors: don’t conduct electricity as well as metals –Ductile and malleable

31. 4. Noble Gases (inert gases) Group 18 (He, Ne, Ar, Kr, Xe, Rn) Normally non-reactive Less than 1% of atmosphere

32. Noble gases glow brightly when an electric charge is passed through them, and so are used as advertising signs: neon tubes glow red, xenon blue, and krypton bluish-white; argon tubes glow pale red at low pressures, blue at high pressures.

33. Summary: 1.Explain how the periodic table of elements is arranged. 2.What are the various pieces of information that can be found in an element key? 3.Explain some of the properties of metals. 4.Explain some of the properties of nonmetals. 5.Explain some of the properties of metalloids. 6.Explain some properties of noble gases.

34. Review: 1.Elements in the periodic table are arranged by a.atomic number b.atomic weight c.number of neutrons d.chemical reactivity

35. 2. Which of these things will you NOT find in the periodic table? a.Element symbol b.Atomic weight c.Atomic orbital radius d.Atomic number

36. 3. Elements at the left of the periodic table are known as a.Nonmetals b.Metals c.Noble Gases d.Metalloids

37. 4. Elements at the right of the periodic table are known as a.Nonmetals b.Metals c.Noble Gases d.Metalloids

38. 5. Which element is a metalloid? a.S (Sulfur) b.Si (Silicon) c.Ba (Barium) d.Br (Bromine)