1. Ch. 5: Periodic Law

2. Quest Assignment
Ch. 5: Periodic Trends
Due 11/11

3. 1s1
2s1
2s2
2p1
2p2
2p3
2p4
2p5
2p6
3s1
3s2
3p1
3p2
3p3
3p4
3p5
3p6
4s1
4s2
4p1
4p2
4p3
4p4
4p5
4p6
5s1
5s2
5p1
5p2
5p3
5p4
5p5
5p6
6s1
6s2
6p1
6p2
6p3
6p4
6p5
6p6
7s1
7s2
7p1
7p2
7p3
7p4
7p5
7p6

4. Valence Electrons Neon Argon Radon
The electrons on the outside edge of the atom
This is where the action is- where bonding takes place
Atoms have no more than 8 valence electrons
Neon
1s22s22p6
Argon
1s22s22p6 3s23p6
Radon
[Xe]6s24f 145d106p6

5. Maximum Number of Electrons Max number of Valence Electrons
Energy Level (Shell)
Maximum Number of Electrons
Max number of Valence Electrons 1 2 8 3 18 4 32 5 50 6 72 7 98

6. Valence Electrons
The highest principal energy level is called the valence level, or valence shell
The valence level contains electrons that are furthest from the nucleus (on the outside edge) and highest in energy
Inner-level electrons are called core electrons
Valence electrons are important in chemical reactions

7. The Octet Rule:
Atoms will combine to form compounds in order to reach eight electrons in their outer energy level.
Atoms with less than 4 valence electrons tend to lose electrons.
Atoms with more than 4 valence electrons tend to gain electrons.

9. Boron will seek to gain 5 electrons.
True
False
Non-Response Grid
26 of 26

10. How many valence electrons does Si (Z=14)have?2 4 6 8 8%
65% 4%
23%
Non-Response Grid
26 of 26

11. How many valence electrons does Re (Z = 75)have?8 7 5 2 4% 0%
96%
Non-Response Grid
26 of 26

12. History of the Periodic Table
1750
only 17 elements had been discovered
1789: Antoine Lavoisier (about 30)
Grouped known elements into four categories
Metals, earths, nonmetals, gases
1860
More than 60 elements

13. Mendeleev and the Periodic Table
If elements are arranged in atomic mass order, similarities in chemical properties appeared at regular intervals (were periodic)
He left empty spaces for undiscovered elements, which were later found

14. What does periodic mean?

15. 1869: Dmitri Mendeleev Published first periodic table
Discrepancies existed
Lothar Meyer published similar table in Arranged by atomic volume.

17. 1911: Henry Moseley
Confirmed Mendeleev’s work with one important change
Ordered elements by properties and atomic number
Periodic Law: the physical and chemical properties of the elements are periodic functions of their atomic numbers
Used spectral analysis. Found that elements fit into the patterns better if arranged by nuclear charge.

18. Periodic Table
An arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same column.

19. Modern Periodic Table
Presently, 118 elements listed, although not all of them have been confirmed

20. Sections to know: Metals, nonmetals, metalloids

21. Periods on the Periodic Table
Horizontal rows
Called periods or series
Numbered 1, 2, 3, ….
Include representative elements and transition elements

22. Periods on the Periodic Table1 2 3 4 5 6 7

23. Groups or Families
Vertical columns
Similar chemical properties

24. Representative Groups on the Periodic Table

25. Group 1 Elements Group 1: Alkali Metals (Li, Na, K, Rb, Cs, Fr)
Not hydrogen
Silvery appearance, very soft, very reactive
Form +1 ions

26. Group 2 Elements
Group 2: Alkaline Earth Metals (Be, Mg, Ca, Sr, Ba, Ra)
Harder and stronger
Very reactive
Form +2 ions
Groups 1 & 2 never found in nature as free elements

27. Group 17 Elements Halogens (F, Cl, Br, I) Most reactive nonmetals
Form -1 ions
Fluorine very reactive!

28. Group 18 Elements Noble Gases ( He, Ne, Ar, Kr, Xe, Rn)
Generally unreactive
Often found in nature in elemental state
Don’t form ions

29. Location of Some Groups A
l m
k e
a t
l a
i l s A l k a i n e H a l o g e n s
I G
n a
e s
r e
t s

30. Name
Symbol
Charge As
hypoiodite
pertechnetate

31. What element is in Group 17, period 4?Br Mn Cl I 0%
Non-Response Grid
0 of 20

32. What is the Element in Group 2, period 3
Beryllium
Magnesium
Boron
Calcium 0%
Non-Response Grid
0 of 20

33. Which element is a Metal in group 14?Zn Ge Pb 0%
Non-Response Grid
0 of 20

34. Which element is a nonmetal in group 15
Sulphur
Tin
Phosphorus
Silicon 0%
Non-Response Grid
0 of 5

35. Learning Check E5 Specify metal (1) or nonmetal (2) for each:
A. sulfur ____
B. chlorine ____
C. sodium ____
D. iron ____
E. Carbon ____
F. silver ____

36. Solution E5 Specify metal (1) or nonmetal (2) for each:
A. sulfur __2__
B. chlorine __2__
C. Sodium __1__
D. iron __1__
E. Carbon __2__
F. silver __1__

37. Other classifications
Transition metals
B Group
Lanthanides
Actinides

38. Actual arrangement
Lanthanides Transition
Actinides

39. Periodicity
The arrangement of the elements on the periodic table so that their chemical properties repeat at various intervals according to the periodic law
Accounts for the shape of the table and the s, p, d, and f blocks

40. Using the Periodic Table for Electron Configurations
Blocks contain elements with the same highest-energy sublevel.

41. The Periodic Table and Order of Fill

42. Electron-dot diagrams can be used to give the number of valence electrons
The number of valence electrons is equal to the element’ group number or group # -10

43. iodine phosphorus gallium argon
Write the electron-dot symbols for the following elements:
iodine phosphorus gallium argon

45. Name
Symbol
Charge
TeO3
tungstate
HSeO4

46. Name
Symbol
Charge As
hypoiodite
pertechnetate

47. Periodic Trends Valence electrons participate in chemical reactions
same group =same number of valence electrons
very similar reactivities
 can make generalizations
Figure 7.25

48. Factors Affecting Change in Properties
Some terms
Valence: highest energy level electrons
Kernel: Everything else in the atom
Nucleus
Inner level electrons

49. Factors Affecting Change in Properties
As you move left right:
Atomic number increases
Greater positive charge in the nucleus

50. Factors Affecting Change in Properties
Moving across a series of elements
Lithium Boron Nitrogen
[He] 2s [He] 2s2 2p [He] 2s2 2p3
kernel: 3p+ + 2e p+ + 2e p+ + 2e-
net charge:

51. Factor #1
A greater net positive charge results in an increased attraction of electrons to the nucleus

52. Factors Affecting Change in Properties
As you move down a column:
Lithium Sodium Potassium
[He] 2s [He]2s2p63s [He]2s22p6
3s23p64s1
Valence electrons are further from the nucleus.

53. Factor #2
More energy levels result in the outer electrons feeling less attraction to the nucleus (further away)

54. Factor #3 Shielding occurs:
More inner shell electrons cause outer shell to be repulsed

55. Factor #4
There is a greater stability associated with half-filled and filled sublevels
Electrons move closer together

56. Name
Symbol/Formula
Charge Ra
Bromite

57. Atomic Size Atomic size is often described in terms of atomic radius.
Atomic radius is the distance from the center of the nucleus to the outer edge of the atom.
Remember the four factors:
Across a period, what happens?
Down a group, what happens?
Across: A greater net positive charge results in an increased attraction of electrons to the nucleus.
Down: More energy levels result in the outer electrons being further away.

58. Trends in Atomic Size
The general trend for atomic size (or radius) is for atomic size to increase from top to bottom and decrease from left to right.

59. Trends in Atomic Size

60. Ions
An atom or group of bonded atoms that has a positive or negative charge
A positive ion is called a cation
A negative ion is called an anion

61. Electron configuration of ions
Element
Atom
Ion
Sodium
Na 1s2 2s2 2p6 3s1
Na+ 1s2 2s2 2p6
Magnesium
Mg 1s2 2s2 2p6 3s2
Mg+2 1s2 2s2 2p6
Fluorine
F: 1s2 2s2 2p5
F- 1s2 2s2 2p6
Oxygen
O: 1s2 2s2 2p4
O-2 1s2 2s2 2p6

62. Ionization Energy
The energy required to remove one electron from a neutral atom of an element
(How easy or hard it is to take a valence electron from a gaseous atom to form a gaseous ion)
Results in an ion with a +1 charge
Energy is required
A + energy A+ + e-

63. Trends in Ionization Energy

64. Removing electrons from positive ions
The energies for removing additional electrons from an atom are called:
Second ionization energy
Third ionization energy
Fourth ionization energy
IE’s become increasingly large as more electrons are removed

65. Greatest jump in energy occurs when an ion reaches a noble gas configuration
Li+1 : 1s2
Be +2 : 1s2
B+3 : 1s2

66. Look at blue boxes

67. Electron Affinity
The energy change that occurs when an electron is acquired by a neutral atom
Results in the formation of an ion with a -1 charge
Energy is usually released
A + e A- + energy

70. Ionic Radii Forming a cation decreases the atomic radius
Loss of highest energy level electrons
Greater pull of the nucleus on fewer electrons
Forming an anion increases the atomic radius
No increase in nuclear charge
Greater repulsion between electrons

72. Electronegativity
The measure of the ability of an atom in a compound to attract bonding electrons to itself
Scale developed by Linus Pauling
Fluorine is the most electronegative atom, with a value of 4.0

73. Periodic Trend — Electronegativity

75. Metals and Nonmetals Metals Located to the left of stairs Luster
Ductile
Malleable
Good conductors

76. Metals and Nonmetals Nonmetals Metalloids Located to right of stairs
Dull
Brittle
Poor conductors, good insulators
Metalloids
Some properties of both metals and nonmetals (semiconductors)

77. Metallic Character Decreases from left to right
Increases from top to bottom

79. Periodic Trend — Ionization Energy Stability of ½ filled and filled sublevels

82. Periodic Trend — Ionization Energy Stability of ½ filled and filled sublevels
The order will be reversed:
Groups 2 and 13
Groups 15 and 16

83. Periodic Trend — Electron Affinity Stability of ½ filled and filled sublevels

85. Periodic Trend — Electron Affinity Stability of ½ filled and filled sublevels
The order will be reversed:
Groups 1 and 2
Groups 14 and 15