1. The Periodic Table and trends
The how and why

2. History 1829 German J. W. Dobereiner Grouped elements into triads
Three elements with similar properties
Properties followed a pattern
The same element was in the middle of all trends
Not all elements had triads

3. History
Russian scientist Dmitri Mendeleev taught chemistry in terms of properties
Mid 1800 – atomic masses of elements were known
Wrote down the elements in order of increasing mass
Found a pattern of repeating properties

4. Mendeleev’s Table
Grouped elements in columns by similar properties in order of increasing atomic mass
Found some inconsistencies - felt that the properties were more important than the mass, so switched order.
Found some gaps
Must be undiscovered elements
Predicted their properties before they were found

5. The Modern Table Elements are still grouped by properties
Similar properties are in the same column
Order is in increasing atomic number
Added a column of elements Mendeleev didn’t know about.
The noble gases weren’t found because they didn’t react with anything.

6. Horizontal rows are called periods
There are 7 periods

7. Vertical columns are called groups.
Elements are placed in columns by similar properties.
Also called families

8. The elements in the A groups are called the representative elements

9. IA IIA IIIB IVB VB VIB VIIB VIIIB IIIA IVA VA VIA VIIA VIIIA IB IIB 1
Other Systems IA
IIA
IIIB
IVB VB
VIB
VIIB
VIIIB
IIIA
IVA VA
VIA
VIIA
VIIIA IB
IIB 1 2 13 14 15 16 17 18 3 4 5 6 7 8 9 10 11 12 1A 2A 3A 4A 5A 6A 7A 8A 3B 4B 5B 6B 7B 8B 1B 2B

10. Metals

11. Metals Luster – shiny. Ductile – drawn into wires.
Malleable – hammered into sheets.
Conductors of heat and electricity.

12. Transition metals
The Group B elements

13. Non-metals
Dull
Brittle
Nonconductors- insulators

14. Metalloids or Semimetals
Properties of both
Semiconductors

15. These are called the inner transition elements and they belong here

17. Group 1 are the alkali metals
Group 2 are the alkaline earth metals

18. Group 17 is called the Halogens
Group 18 are the noble gases

19. Why? The part of the atom another atom sees is the electron cloud.
More importantly the outside orbitals
The orbitals fill up in a regular pattern
The outside orbital electron configuration repeats
So.. the properties of atoms repeat.

20. H 1 Li 3 Na 11 K 19 Rb 37 Cs 55 Fr 87
1s1 1s22s1 1s22s22p63s1 1s22s22p63s23p64s1 1s22s22p63s23p63d104s24p65s1 1s22s22p63s23p63d104s24p64d105s2 5p66s1 1s22s22p63s23p63d104s24p64d104f145s25p65d106s26p67s1

21. 1s2 1s22s22p6 1s22s22p63s23p6 1s22s22p63s23p63d104s24p6 1s22s22p63s23p63d104s24p64d105s25p6 1s22s22p63s23p63d104s24p64d105s24f14 5p65d106s26p6 He 2 Ne 10 Ar 18 Kr 36 Xe 54 Rn 86

22. S- block s1 s2 Alkali metals all end in s1
Alkaline earth metals all end in s2
really have to include He but it fits better later
He has the properties of the noble gases

23. Transition Metals -d block

24. The P-block p1 p2 p3 p4 p6 p5

25. F - block f1 f5 f2 f3 f4 f6 f7 f8 f9 f10 f11 f12 f14 f13
inner transition elements f1 f5 f2 f3 f4 f6 f7 f8 f9
f10
f11
f12
f14
f13

26. Each row (or period) is the energy level for s and p orbitals1 2 3 4 5 6 7
Each row (or period) is the energy level for s and p orbitals

27. d orbitals fill up after previous energy level so first d is 3d even though it’s in row 41 2 3 4 5 6 7 3d

28. 1 2 3 4 5 6 7 4f 5f
f orbitals start filling at 4f

29. Writing Electron configurations the easy way
Yes there is a shorthand

30. Electron Configurations repeat
The shape of the periodic table is a representation of this repetition.
When we get to the end of the row the outermost energy level is full.
This is the basis for our shorthand

31. The Shorthand
Write the symbol of the noble gas before the element in brackets [ ]
Then the rest of the electrons.
Aluminum - full configuration
1s22s22p63s23p1
Ne is 1s22s22p6
so Al is [Ne] 3s23p1

32. More examples Ge = 1s22s22p63s23p63d104s24p2 Ge = [Ar] 4s23d104p2
Ge = [Ar] 3d104s24p2
Hf=1s22s22p63s23p64s23d104p64f14 4d105s25p65d26s2
Hf=[Xe]6s24f145d2
Hf=[Xe]4f145d26s2

33. Electron configurations and groups
Representative elements have s and p orbitals as last filled
Group number = number of electrons in highest energy level
Transition metals- d orbitals
Inner transition- f orbitals
Noble gases s and p orbitals full