Chapter 5

1. Chapter 5 The Periodic Table

2. Section 5.1 Organizing elements

3. Section 1: Organizing Elements a. Dmitri Mendeleev was the first to design a way of organizing elements

4. Arranged elements in rows by increasing atomic masses • Started a new row each time chemical properties repeated • Left gaps in his list for elements that had not been discovered yet • Some elements did not fit Mendeleev’s pattern

5. b. Henry Moseley arranged elements by atomic numbers i. Most elements did not change their location, but a few did

6. c. The modern periodic table organizes elements by atomic number d. When the elements are arranged this way, elements that have similar properties appear at regular intervals (periodic law)

8. e. Period: each row of the periodic table i. There are 7 periods on the periodic table ii. As you move to the right across a period, elements become less metallic

9. f. Groups: each column on the periodic table i. each group has similar chemical properties ii. There are 18 groups on the periodic table

10. Do section 1 review sheet

11. Section 1 review • 1. Describe how Mendeleev organized his periodic table • By increasing atomic masses • Started a new row each time chemical properties repeated • Left gaps for undiscovered elements

12. Section 1 review • 2. Explain why Mendeleev left a space for the unknown (at the time) element germanium in his periodic table. • The properties of germanium did not match the next available group, so he moved it over to the group whose properties germanium did match, and left a space

13. Section 1 review • 3. State the property used to organize elements in the modern table. • Atomic number

14. Section 1 review • 4. Identify the following on the periodic table: • The chemical symbol for mercury • Hg • The period and group of gold • Period 6 • Group 11 • The atomic mass of iron • 55.845

15. Section 1 review • 4. Identify the following on the periodic table: • The atomic number of neon • 10 • The element represented by Cu • copper

16. Section 1 review • 5. Metals conduct electricity well, while nonmetals do not. Which element should conduct electricity better: germanium, aluminum or helium? • aluminum

17. Section 1 review • 6. Are the properties of sodium (Na) more like the properties of lithium (Li) or magnesium (Mg)? Explain your answer. • Lithium—they are in the same group (column)

18. Section 1 review • 7. Find oxygen (O), sulfur (S), and fluorine (F) in the periodic table. Are the chemical properties of O more similar to those of S or F? Explain your answer. • Sulfur—they are in the same group (column) What is wrong here?!!!

19. Section 1 review # 8 6 11 Au 79 196.966569 5 silver Ag 107.8682 11 20 Ca calcium 40.078 4 55.845 8 iron 26

20. Section 1 review • 9. If scientists found element 117, into which period and group would they place it? Identify one element that would have properties similar to those of element 117. • Period 7, group 17 • Like F, Cl, Br, I or At

21. Section 5.1 Review

22. matching E G • _____ 1. the repeating chemical & physical properties of elements change periodically with the atomic numbers of the elements • _____ 2. a horizontal row of elements in the periodic table • _____ 3. a vertical column of elements in the periodic table • _____ 4. Mendeleev arranged the elements in rows by increasing ___ ___. • _____ 5. The modern periodic table organizes elements by ___ ___. • _____ 6. the first man to design a way to organize the elements • _____ 7. the man who arranged the elements by atomic number • _____ 8. the number of periods on the periodic table • _____ 9. the number of groups on the periodic table • A. atomic mass B. atomic number C. 18 D. 7 • E. periodic law F. Group G. period • H. Moseley I. Mendeleev F A B I H D C

23. Use the periodic table: Mo • _____ 10. the chemical symbol for molybdenum • _____ 11. what period is molybdenum in? • _____ 12. what group is molybdenum in? • _____ 13. the atomic number of molybdenum • ____________ 14. the atomic mass of molybdenum • _____ 15. the chemicalsymbol for an element that has properties similar to molybdenum 5 6 42 95.94 Cr, W Sg

24. Use the periodic table: Os • _____ 16. the chemical symbol for osmium • _____ 17. what period is osmium in? • _____ 18. what group is osmium in? • _____ 19. the atomic number of osmium • ____________ 20. the atomic mass of osmium • _____ 21. the chemicalsymbol for an element that has properties similar to osmium 6 8 76 190.23 Fe, Ru, Hs

25. Use the periodic table: Pt • _____ 22. the chemical symbol for platinum • _____ 23. what period is platinum in? • _____ 24. what group is platinum in? • _____ 25. the atomic number of platinum • ____________ 26. the atomic mass of platinum • _____ 27. the chemicalsymbol for an element that has properties similar to platinum 6 10 78 195.084 Ni, Pd, Ds

27. 1 18 2 13 14 15 16 17 3 4 5 6 7 8 9 10 11 12 6 7

28. Practice: Periodic Table and Valence Electrons

29. Questions • Definition of period • Horizontal row • Definition of group • Vertical column • What tells the # of valence electrons? • Group number (for 13-18, subtract 10) • What tells the number of energy levels? • Period number

30. Chart

31. Chart

32. Section 5.2 Exploring the periodic table

33. B. Section 2: Exploring the Periodic Table a. The periodic trends in the periodic table are a result of electron arrangement

34. i. The chemical properties of each group are determined by the number of valence electrons ii. The atoms of elements in the same group have the same number of valence electrons Number of valence electrons 8 2

35. The period tells you the number of energy levels!!!

36. The period tells you the number of energy levels!!!

37. b. Ion formation i. Ionization: an atom may gain or lose valence electrons so its outermost energy level is full

38. ii. If an atom gains or loses electrons, it no longer has an equal number of electrons and protons iii. Because the charges do not cancel completely, the atom has a net electric charge (ion) 2, 8, 1 2, 8, 7 Sodium: 11 protons 11 electrons Chlorine: 17 protons 17 electrons Sodium ion (+1): 11 protons 10 electrons Chloride ion (-1): 17 protons 18 electrons 2, 8 2, 8, 8

39. iv. Group 1 elements 1. very reactive 2. have one valence electron which can be easily removed 3. when an atom loses an electron it becomes positive All of this is true of hydrogen, although it is NOT a full member of this group!

40. 4. positive atoms are called cations and are written with a superscript “+” next to the element symbol 5. For example, a lithium (Li) ion with a charge of +1 is written Li+ or Li1+ or Li+1

41. v. Group 17 elements 1. very reactive 2. have 7 valence electrons 3. needs only one more to become stable

42. 4. when an atom gains an electron, it is called an anion, and is written with a superscript “-” next to the element symbol 5. For example: a fluorine (F) ion with a charge of -1 is written F- or F1- or F-1

43. vi. Other groups 1. Groups 2-16 can also form ions 2. have to lose or gain more than one electron in order to fill their outermost energy level

44. 3. In general: a. atoms with fewer than four valence electrons lose electrons to form cations (positive ions) b. atoms with more than four valence electrons gain electrons to form anions (negative ions)

45. 4. Ions of these elements are also indicated with superscripts, however, the symbols for these ions also show how many electrons were gained or lost 5. For example: magnesium (Mg) loses its two valence electrons to form a cation Mg2+

46. c. How are elements classified i. three categories: metals, nonmetals, and semiconductors (metalloids)

47. Metals Nonmetals Semiconductors metalloids

48. Lead

50. Tellurium metalloids