Periodic Table

Long form periodic table: Based on:

1) Energy sub levels (s, p, d and f)
2) Auf Beau principle

Elements arranged in an ascending order according to their atomic numbers and the sequence of elements agrees with the building up (Auf-beau) principle
Atoms with similar electron configurations are placed in the same column. The columns are called groups
For example: All of elements in Group 1 (the alkali elements), have single electron and display similar properties of chemical reactivity, formation of oxides, etc.
Features of the periodic table are:

7 horizontal periods
16 vertical groups (18 columns)

The 7 horizontal periods:

Elements in a period have consecutive atomic numbers
Each period contains more elements than the previous one. This has to do with the increasing energy levels (n = 1, ...) of the atom

Period 1: n=1(1s) Filled with 2 electrons ...... 2 elements

Period 2: n=2 (2s, 2p) s filled with 2 electrons, p filled with 6 electrons ...... 8 elements

period 3: n=3 (3s, 3p) s filled with 2 electrons, p filled with 6 electrons ...... 8 elements

Period 4: n=4 (4s, 4p, 4d) s filled with 2 electrons, p filled with 6 electrons, d filled with 10 electrons ...... 18 elements

Period 5: n=5 (5s, 5p, 5d) s filled with 2 electrons, p filled with 6 electrons, d filled with 10 electrons ...... 18 elements

Period 6: n=6 (6s, 6p, 6d, 6f) s filled with 2 electrons,p filled with 6 electrons,d filled with 10 electrons,f filled with 14 electrons .....32 elements

Period 7: n=7 (7s, 7p, 7d, 7f) s filled with 2 electrons,p filled with 6 electrons,d filled with 10 electrons,f filled with 14 electrons .....32 elements

The 16 vertical groups (18 columns):

Elements in a group do not have consecutive atomic numbers
Elements of the same group (column) have the same valence electrons or configuration
The groups are divided into A and B groups
Group 1A to 8A has all the normal elements
Group 1B to 8B holds all the transition metal elements
The other two groups are the lanthanide and the actinide series. They are also known as inner transition elements