The periodic table arranges all known elements in order of increasing atomic number and recurring chemical properties. Elements are organized into rows and columns, with each row representing an orbital period and each column representing a group of elements with similar electron configurations and properties. The periodic table has evolved over time as new elements were discovered and theories on atomic structure advanced, leading to the modern form that organizes elements based on their atomic numbers.

1. Periodic Table
The periodic table is an arrangement of all the elements known to man in accordance with
their increasing atomic number and recurring chemical properties. They are assorted in a
tabular arrangement in which a row is a period and a column is a group.

2. History of Periodic Table
Metal Non-Metal
Mercury (Hg) Oxygen (O2)
Zinc (Zn) Hydrogen (H2)
Nitrogen (N2)
Phosphorus (P)
Sulfur (S)
1789
Antoine
Lavoisier
1 33
Elements
 On the basis of physical properties

3. History of Periodic Table
1829
Döbereiner
2
Cl I
Br
Cl I
2
Atomic
mass

4. History of Periodic Table
2
Döbereiner’s Law of triads

5. History of Periodic Table
1862
De
Chancourtoi
3
Characteristics:
 Based on atomic mass.
 Arranged in a rotating way in a perpendicular cylinder.
 Arranged in such a way that the positional height of the element is
proportional to the atomic mass of the element.
 Elements with similar characters are located just below each other.
 The first step of modern periodic table.

6. History of Periodic Table
1864
John Newlands
4
 Arranged elements in an ascending
order based on their atomic masses
 Observed that every 8th element
had similar properties.

7. History of Periodic Table
Lothar
Meyer
5
 not only ordered the elements with increasing
atomic weights but also grouped them
according to their valencies.
 Plotted the graph of the atomic volume (molar
volume) vs atomic mass.

8. History of Periodic Table
1869
Dimitri Mendeleev
6
Law of the Mendeleev’s periodic table:
the properties of elements are the periodic functions of their atomic
masses.
63 invented
elements and 4
non invented
element

9. History of Periodic Table
6
The similarity of the modern periodic table with the early periodic table
given by Mendeleev is negligible.
Three years later, Mendeleev
rearranged his periodic table in a
slightly different way, similar to
the modern periodic table.

10. History of Periodic Table
6
Limitations of Mendeleev’s periodic table:
 Argon (39.94) and Potassium (39.1), Tellurium (127.5) and Iodine (126.9), Cobalt (58.9) and Nickel
(58.7)- In these three cases it was not possible to sort by mass.
 No proper position could be given to the element Hydrogen.
 Position of the isotopes could not be explained.
 Problems with lanthanides and actinides.
 8th group incompatibility.

11. History of Periodic Table
Modern era
7
 In 1913, Henry G. J. Moseley observed that the order of characters of elements was changing on the basis of
atomic numbers, not atomic masses.
 Then the periodic formula slightly changed- The physical and chemical properties of elements rotate
gradually as their atomic numbers increase.

13. Characteristics of modern periodic table
 7 periods (horizontal row)
 18 groups (vertical column)
 A small table composed of 2 horizontal rows and 14 perpendicular columns is displayed
beneath the main periodic table. It is also the part of period-6 and period-7 of main
periodic table.
 Properties of the elements change from left to right in the same period.
 The physical and chemical properties of elements of the same group are almost similar.
Period 1 2, 3 4, 5 6, 7
Number of elements 2 8 18 32
Group 1 2 3 4-12 13-17 18
Number of elements 7 6 32 4 6 7
Number
of
elements

14. Determination of the position of elements in periodic table from the electronic configuration
Determining the period number:
 The number of the outermost main energy level ---> Period number of that
given element.
For example,
 Li (3) ---> 1s² 2s¹
Here, period number of Li is 2
 Mg (12) ---> 1s² 2s² 2p6 3s².
Here, period number of Mg is 3
 Ca (20) ---> 1s2 2s2 2p6 3s2 3p6 4s2
Here, period number of Ca is 4

15. Determination of the position of elements in periodic table from the electronic configuration
Determining the group number
If Last Electron enters –
 s block – it is a s block elemen
 p block – it is a p block elemen
 d block – it is a d block elemen

16. Determination of the position of elements in periodic table from the electronic configuration
Determining the group number
Valence Shell
 A valence shell is the outermost electron-containing
shell of an atom.
 The electrons in this shell are called valence
electrons.
Penultimate Shell
 Penultimate shell is the electron-containing shell
that is inner to the outermost valence shell.
 It is the second last electron-filled shell or the shell
before the valence shell.
Valence Shell
Penultimate Shell

17. Determination of the position of elements in periodic table from the electronic configuration
Determining the group number:
 If it is an element of s block ---> The number of electrons in the valence shell.
Be (4) ---> 1s² 2s²
Francium (87) ---> 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s1

18. Determination of the position of elements in periodic table from the electronic configuration
Determining the group number:
 If it is an element of p block ---> The number of electrons in valence shell (summation of
outermost electrons present in s and p orbitals) + 10
N (7) ---- > 1s² 2s² 2p³
Oganesson (118) ---- > 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d10 7p6

19. Determination of the position of elements in periodic table from the electronic configuration
Determining the group number:
 If it is an element of d block ---> The number of electrons in valence shell +
The number of electrons in the penultimate shell (very near to the valence shell).
Fe (26) ---> 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶
Ag (47) ---> 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d10

20. Electronic configurations of the elements are the main
basis of the periodic table

21. The Special Names of Elements Present in Various Groups
Name of the group Special Name
1 Alkali metal
2 Alkaline earth metal
15 Pnictogen
16 Chalcogen
17 Halogen
18 Inert gas / Noble gas
3-12 Transition metal
 Coin metals — Cu, Ag, Au
 Acid earth metals — V, Nb, Ta
 Volatile metals — Zn, Cd, Hg
 Lanthanides — Elements 57–71
 Actinides — 89–103
 Rare-earth element — Sc, Y, Lanthanides.

22. Some Exceptions of Periodic Table
 The position of Hydrogen
 The position of Helium
 The position of Lanthanide and Actinide groups

23. Periodic Properties of Elements
The phenomenon in which repetition of similar properties of elements occurs are called periodic
properties.
 Metallic Properties
 Non-Metallic Properties
 Atomic Radius / Size of Atom
 Ionization Energy (ionization potential)
 Electron Affinity
 Electronegativity

24. Metallic and Non-Metallic Properties

25. Metallic and Non-Metallic Properties
Metallic Properties
Decreases
Decreases

26. Metallic and Non-Metallic Properties
Non-Metallic Properties
Increases
Increases

27. Atomic Radius / Size of Atom
Atomic Radius / Size of Atom
Top to bottom in the same group

28. Atomic Radius / Size of Atom
Atomic Radius / Size of Atom
Left to right in the same period
Li Be B C N O F Ne

29. Atomic Radius / Size of Atom
Atomic Radius / Size of Atom

30. Ionization Energy
Ionization energy is simple terms can be described as a measure of the difficulty in removing an electron
from an atom or ion or the tendency of an atom or ion to surrender an electron.
1st Ionization Energy, X – e- → X+
2nd Ionization Energy, X+ – e- → X2+
3rd Ionization Energy, X2+ – e- → X3+
The energy that is required to transform an element into one mole
positive ion removing one mole electron from its one mole atom
in its gaseous state is called ionization energy of that element.

31. Ionization Energy
Ionization Energy
Increases
Increases

32. Electron Affinity
The energy emitted when we try to transform an element in its gaseous state
into one mole negative ion by injecting one mole electron into its one mole
atom is called the electron affinity of that element.

33. Electron Affinity
Electron Affinity
Increases
Increases

34. Electronegativity
When two atoms turn into a molecule in covalent bond , the atoms in that
molecule attract he electrons toward themselves. This attraction is called
electronegativity.
When the electronegativity is more

35. Electronegativity
Electronegativity
Increases
Increases

36. Periodic Properties of Elements
Shell Number Remains same
Increases
by
one
Ionization Energy
Electron Affinity
Electronegativity
Increases
Increases
Increases
Decreases
Decreases
Decreases
Metallic Properties
Non-Metallic Properties
Size of Atom
Decreases
Decreases
Decreases
Increases
Increases
Increases

38. Some Interesting Facts about the Periodic Table
 The only English letter not in the periodic table- J
 The rarest element found in the earth- Astatine (At)
 The first artificially created element- Technetium (Tc)
 75% of the periodic table is metal
 The 136th element may be the last element