Bell Ringer - Riddles

1. Bell Ringer - Riddles • The man who invented it doesn't want it. The man who bought it doesn't need it. The man who needs it doesn't know it. What is it? • I run over fields and woods all day. Under the bed at night I sit not alone. My tongue hangs out, up and to the rear, awaiting to be filled in the morning. What am I? • Throw it off the highest building, and I'll not break. But put me in the ocean, and I will. What am I? • What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps? • No sooner spoken than broken. What is it?

2. Answers to Riddles • A tissue or a wave • A coffin • A shoe

3. Answers to Riddles cont. • A river • Silence or a secret

4. The Periodic TableChapter 5 p.133-164 History Structure Trends

5. Section I: Attempts at Classification

6. Dobereiner - 1817 • Discovered groups of three elements with similar properties • “Triads” • Ca – 40 amu • Sr – 87.6 amu • Ba – 137 amu Mass of Sr is about ½ way between Ca and Ba

7. Newlands - 1863 • Arranged elements in order of increasing atomic mass • Found a repetition of similar properties with every 8th element • “Law of octaves” • 7 column table with 7 rows

8. Mendeleev - 1870 • Arranged elements in order of atomic mass with 8 long columns and several short columns • Arrangement reflected properties of the elements • Predicted existence of several elements to fill gaps in his table • These elements were later discovered and had the properties predicted

9. Mendeleev’s Periodic Law Properties of the elements are a periodic function of their atomic masses.

10. Moseley - 1913 • Performed experiments to determine an accurate mass for several elements which seemed out of place on the table • Noticed a pattern in the number of protons • Reorganized elements in order of atomic number rather than mass

11. Modern Periodic Law: The physical and chemical properties of elements are periodic functions of their atomic numbers.

12. Modern Periodic Table • Most significant addition to Mendeleev’s periodic table came with the discovery of the noble gases. • A new row was added to the periodic table after their discovery.

13. Section II: The Modern Periodic Table

14. 1 2 3 4 5 6 7 Periods • 7 rows • Can be determined from the element’s electron configuration (ec) • Example: arsenic has an ec= [AR] 3d104s24p3 the 4 in 4p3 means that arsenic is in the fourth period

15. Periods

16. Groups or Families • 18 columns

17. Groups or Families • The group number is the same as the number of electrons in the outermost energy level of an atom. • Except groups 10 though 18. The number of electrons in the outermost energy level of the atom is the group number -10. • Example: Group 18 is the noble gases 18 – 10 = 8 We already knew that noble gases have 8 electrons in their outermost energy level.

18. This Arrangement Reflects: • Properties • Increasing atomic number • Electron configuration

19. Electron Configuration: Li Li – 1s22s1 Na – 1s22s22p63s1 K – 1s22s22p63s23p64s1 Na K Same Family or Group All have 1 e- in the outer level All are similar in color and hardness All react vigorously with water All belong to family/group 1

20. Electron Configuration: C - 1s22s22p2 N - 1s22s22p3 O - 1s22s22p4 C N O Same period All have a full 1st energy level with e- in s and p orbitals of the second level Number of e- is increasing by 1 All are in period 2

21. Blocks: • Based on the electron configurations of the elements, the periodic table can be divided into four blocks, the s, p, d, and f blocks.

22. Blocks: p d s f

23. Classification of Elements: • Most of the elements are metals. • Located on the left side of the table.

24. General Properties of Metals: • 1 to 3 e- in outer energy level of most • Lose e- to form bonds (+ ions) • Shiny • Hard • Good conductors of heat • Good conductors of electricity

25. Classification of Elements Cont.: • Some elements are nonmetals and are found on the right side of the table.

26. General Properties of Nonmetals: • 5 to 8 electrons in the outer level • Gain e- to form bond (- ions) • Brittle solids or gases • Poor conductors of heat • Poor conductors of electricity

27. Classification of Elements: • Some elements have properties similar to both metals and nonmetals. • These are found bordering the stair-step dividing line. • Exception: Al is a metal • These elements are called metalloids.

28. metals metalloids nonmetals

29. 1 – alkali metals 2 – alkaline earth metals 3-12 – transition metals 16 – chalcogens 17 – halogens 18 – noble gases Elements 58 – 71 – lanthanides Elements 90 – 103 – actinides Lanthanides and actinides – rare earth metals Some of the Families/Groups Have Special Names.

31. Think about trends!!! • Trend- to show a tendency *Mirriam-Webster Online dictionary • I want you to write down every thing that comes to your mind when you hear the word trend.

32. Trends • Since trends are a tendency, they can be used to classify. • In Chemistry, trends are used to arrange elements in the periodic table.

33. Part III: Trends on the Periodic Table

34. Atomic Radius • One-half the distance between the nuclei of identical atoms that are bonded together. • Radius depends on: • the number of energy levels • the strength of the nucleus

35. Each group represents a higher principal quantum number (n) As n increases, size of the e- cloud increases. F Atomic radius increases down a family. Cl Br

36. Across a period, nuclear charge increases by 1 for each element. A stronger nucleus acts like a stronger magnet which attracts the e- cloud. C N O Atomic radius decreases across a period.

39. Na or Rb? Rb Cl or I? I Al or Si? Al K or Ca? K Ag or Au? Au Ni or Cu? Ni La or U? La H or He? H Determine which is larger?

40. Ionic Radius • Size of an ion • Ions are charged atoms formed when: • Atoms lose e- • (+ Ion) • Cation • Atoms gain e- • (- Ion) • Anion

41. Cations- smaller than their respective neutral atoms. Remember that cations are the + charged ions. Metals usually lose all valence electrons. - e- + The nucleus pulls tighter on the remaining electrons. + + more p+ than e-

42. Anions are larger than their respective neutral atoms. Remember that anions are the - charged ions. Nonmetals usually gain electrons to complete the valence shell. + e- - Electrons repel each other and spread out more. - - more e- than p+

44. Ca or Ca+2 Ca F or F–1 F–1 K or K+1 K F-, Ne or Na+ F- O or O-2 O-2 Which is larger?

45. First Ionization Energy • Energy required to remove one electron from a neutral atom of an element. • To avoid the influence of nearby atoms, measurements of ionization energies are made on isolated atoms in the gas phase. • Factors that affect ionization energy: • Radius • Nuclear charge • Shielding effect • Stability of sublevels

46. Radius: • The greater the distance between the nucleus and the valence electrons, the easier it is to lose an electron.

47. Nuclear charge: • Within a period, the higher the nuclear charge, the higher the ionization energy.

48. Shielding Effect: • Other e- block the pull of the nucleus on the outer e-. • Electrons repel each other.

49. Stability of Sublevels: • e- in filled or half-filled sublevels are extremely hard to remove. • Higher ionization energy than their immediate neighbors C N O Highest IE

50. General Trend for IE: Ionization energy increases as you go up a family and across a period.