1. The Periodic Table
The how and why

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

3. 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.

4. 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.

5. Horizontal rows are called periods
There are 7 periods

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

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

8. The group B are called the transition elements
These are called the inner transition elements and they belong here

9. Group 1A are the alkali metals
Group 2A are the alkaline earth metals

10. Group 7A is called the Halogens
Group 8A are the noble gases

11. 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.
The properties of atoms repeat.

12. H 1 Li 3 Na 11 K 19 Rb 37 Cs 55 Fr 87
1s1
1s22s1
1s22s22p63s1
1s22s22p63s23p64s1
1s22s22p63s23p64s23d104p65s1
1s22s22p63s23p64s23d104p65s24d10 5p66s1
1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s1

13. 1s2
1s22s22p6
1s22s22p63s23p6
1s22s22p63s23p64s23d104p6
1s22s22p63s23p64s23d104p65s24d105p6
1s22s22p63s23p64s23d104p65s24d10 5p66s24f145d106p6 He 2 Ne 10 Ar 18 Kr 36 Xe 54 Rn 86

14. 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.

15. Transition Metals -d block

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

17. 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

18. Each row (or period) is the energy level for s and p orbitals.1 2 3 4 5 6 7
Each row (or period) is the energy level for s and p orbitals.

19. D orbitals fill up after previous energy level so first d is 3d even though it’s in row 4.1 2 3 4 5 6 7 3d

20. 1 2 3 4 5 6 7 4f 5f
f orbitals start filling at 4f