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. 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

8. 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.

10. 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

11. What does periodic mean?

12. 1869: Dmitri Mendeleev Published first periodic table
Discrepancies existed
Lothar Meyer published similar table in Arranged by atomic volume.

14. 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.

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

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

17. Sections to know: Metals, nonmetals, metalloids

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

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

20. Groups or Families
Vertical columns
Similar chemical properties

21. Representative Groups on the Periodic Table

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

23. 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

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

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

26. 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

27. Learning Check E3 A. Element in Group 17, Period 4 1) Br 2) Cl 3) Mn
B. Element in Group 2, Period 3
1) beryllium 2) magnesium 3) boron

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

29. Learning Check E6 Select the correct elements: A. Metals in Group 14
1) Ge, Sn, Pb
2) C, Si
3) C, Si, Ge, Sn
B. Nonmetals in Group 15
1) As, Sb, Bi
2) N, P, As
3) N, P, As, Sb

30. Other classifications
Transition metals
B Group
Lanthanides
Actinides

31. Actual arrangement
Lanthanides Transition
Actinides

32. 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

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

35. The Periodic Table and Order of Fill

36. 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

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

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

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

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

41. 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:

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

43. 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.

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

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

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

47. 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.

48. 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.

49. Trends in Atomic Size

50. 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

51. 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

52. 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-

53. Trends in Ionization Energy

54. 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

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

56. Look at blue boxes

57. 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

60. 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

62. 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

63. Periodic Trend — Electronegativity

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

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