1. Periodic Table & Periodic Law
Chapter 6

2. Objectives 6.1
Trace the development and identify key features of the periodic table

3. Development of Modern Periodic Table
Section 6.1

4. History of the Periodic Table
Some elements like Au and Ag were known since prehistoric times
Wikipedia.com

5. Antoine Lavoisier French scientist, late 1790s
Compiled list of 23 elements known at that time
Tried to organize it
Wikipedia.com

6. 1800s Electricity breaks down into component elements
Spectrometer identified newly isolated elements
Industrial revolution (mid-1800s) led to new chemistry related industries
Petrochemicals, soaps, dyes, fertilizers
Created chemical pollution

7. More info
1860
Scientist agreed on method to determine atomic masses
1870
70 known elements

8. John Newlands (1837-1898) 1864 English Chemist
When elements arranged by atomic mass, properties repeated every eighth element
This is periodic since it repeats in pattern
He called this the Law of Octaves
Critics did not like music analogy, law didn’t work for all known elements
Wikipedia.com

9. Newland’s Table

10. Lothar Meyer (1830-1895) 1869 German Chemist
Made connection between atomic mass and element properties
Same time as Mendeleev
Wikipedia.com

11. Dmitri Mendeleev (1834-1907) 1869 Russian chemist
Connection of atomic mass to elemental properties
Gets credit b/c published first and demonstrated its usefulness
Organized first PT
Arranged by atomic mass
Left spaces for “unknown” elements

12. Problems with Mendeleev’s PT
Some element properties did not match up when placed according to atomic mass
Wikipedia.com

13. Mendeleev’s PT

14. Henry Moseley 1913 English chemist who discovered # p+ = atomic #
Arranged PT according to atomic # and “fixed” Mendeleev’s problem
Periodic Law – there is a periodic repetition of chemical & physical properties of elements when arranged by increasing atomic #
Wikipedia.com

15. Moseley’s PT

16. Modern PT Groups – AKA families; columns
Periods – rows; 7 total and growing?
Representative elements – 1A through 8A
Transition elements – 1B through 8B

17. Classifying elements Metals Include most of Group A and all Group B
shiny when smooth and clean
solid at room temp
good conductors of electricity & heat
malleable and ductile
Include most of Group A and all Group B
Group 1A – Alkali metals (except H)
Group 2A – alkaline earth metals
Both groups chemical reactive (1A > 2A)

18. Classifying elements (con’t)
Group B
Transition metals
Inner transition metals
Lanthanides
Phosphors – emit light when struck by e-
Actinides
Wikipedia.com

19. Classifying elements (con’t)
Nonmetals
Located right upper side
Gases or brittle, dull-looking solids
Poor conductors of heat and electricity
Br is only nonmetal liquid at room temp
Halogens (Group 7A)
Noble gases (Group 8A)
Not reactive
Wikipedia.com

20. Classifying elements (con’t)
Metalloids or semi-metals
Have physical and chemical prop of metals and nonmetals
Examples (uses):
Ge (cell phones)
Si (computer chips)
Wikipedia.com

22. Objectives 6.2
Explain why elements in the same group have similar properties
Identify the four blocks of the periodic table based on electron configuration

23. Classification of the Elements
Section 6.2

24. Organizing by e- configuration
Period 1 H 1s s1
Period 2 Li 1s22s [He]2s1
Period 3 Na 1s22s22p63s [Ne]3s1
Period 4 K 1s22s22p63s23p44s1 [Ar]4s1

25. Valence e-
Atoms in the same group have similar chemical properties because they have the same number of valence e-
Group 1A all have 1 e- in last energy level

26. Valence e- and periods
Energy level of element’s valence e- = the period #
Ex: lithium’s valence e- is in the second energy level
Lithium is in the second period

27. Valence e- and group # The group # = the valence e- #
Applies to representative elements ONLY
Ex: Group 5A has 5 e-

28. S-block Group 1A has e- configuration of s1
S orbital is full with 2 e-

29. P-block Group 3A to 8A Holds max of 6 e-
S- and p- blocks comprise all of the representative elements
Noble gases
group 8A
Nearly no chemical rxn
Stable!

30. D-block Contains transition metals Largest block Spans 10 groups
S filled and partially filled d
Ex:
Scandium [Ar]4s23d1
Titanium [Ar]4s23d2

31. F-block Contains inner transition metals
Filled/partially filled s, 4f and 5f
Spans 14 columns

32. Objectives 6.3 Compare period and group trends of several properties
Relate period and group trends in atomic radii to electron configuration

33. Periodic Trends
Section 6.3

34. Atomic radius Atomic size Atomic radius
How close an atom lies to another atom
Atomic radius
Half the distance between adjacent nuclei

35. Atomic Radius Trends DECREASES INCREASES

36. Why does the atomic radius decrease within a period?
Increase # p+ and e-
Each e- is added to the same energy level
Nuclear charge becomes more + as we move from left to right
Valence e- are not shielded from increased nuclear charge
What happens?
Outermost e- pull closer to nucleus

37. Why does the atomic radius increase within a group?
Add energy levels or orbital
Make atom larger
Outer e- are farther away
Valence e- shielded by added distance and not affected by nuclear charge

38. Which has the largest atomic radius?
C, F, Be, or Li
Find the location of the elements.
All P2
Arrange them
Li, Be, C, F
Find your answer Li

39. Ionic radius Atoms can gain or lose e- to form ions
When atoms lose e- and form + ions, they get smaller.
The e- lost is a valence e-
If the orbital is empty, the atom is smaller
If the atom is smaller, the + of the nucleus will pull the remaining e- towards it

40. Ionic radius (con’t)
When atoms gain e- and form (–) ions, they become larger.
Adding e- to outer shell increases electrostatic repulsion between existing e- to move them farther apart.

41. What does the ionic radius do within a period?
Decreases as you move across the period
Refer to page 166 in text
DECREASES

42. What does the ionic radius do within a group?
Increases as you move down the group
Refer to page 166 in text
INCREASES

43. Ionization energy Energy required to remove an e- from a gaseous atom
The energy needed to remove the first e- is called first ionization energy
The amount of energy needed to remove the second e- from a 1+ ion is called the second ionization energy, etc.
The more e- you try to remove, the more energy it takes, and the less likely to occur

44. What does the ionization energy do within a period?
Increases as you move across the period
Removing the last e- makes the nucleus “hold” the remaining e- tighter
INCREASES

45. What does the ionization energy do within a group?
Decreases as you move down the group
Because valence e- are farther from the nucleus, the hold on it is less and takes less energy
DECREASES

46. OCTET RULE
Atoms share, gain, or lose e- to acquire a full set of 8 valence e- (except: period 1 elements)
Elements on right side of table gain e-; form (--) ions
Elements on left side of table lose e-; form + ions

47. Electronegativity The ability for an atom to attract e- to form a bond
Units: Paulings (named after American scientist Linus Pauling)
F is most electroneg
Cs, Fr least electroneg

48. What does the electronegativity do within a period?
Increases as you move across a period
INCREASES

49. What does the electronegativity do within a group?
Decreases as you move down a group
DECREASES

50. Summary of Trends Atomic radius -Size of atom Decrease Left to right
Increase
Top to bottom
Ionic radius
-Size of ion
Ionization energy
-Energy to lose e-
Electronegativity
-Ability to attract e-

51. Credits
Clip art from Microsoft Clip art and Wikipedia as well as other sources documented throughout the presentation
Information obtained mainly from Glencoe Chemistry Matters textbook, Texas ed.
Arranged and explained by Michelle Estrada