Different States of Metals and Non Metals :

Different states of metal and non metal - Teachoo.png

Uses of metals

Metals have various uses in all fields depending upon their physical and chemical properties:

  • Conductors of electricity like Copper and Aluminium are used to make wires
  • Though silver is also an extremely good conductor of electricity, wires are not made from silver since it is very expensive .
  • Iron , Copper , and Aluminium are used to make utensils and equipment due to their malleability, hardness, and good thermal conductivity.
  • Zinc , Copper and Aluminium are used as protective metals to prevent other metals from corrosion.
  • Zinc is used to protect Iron from rusting . The process of placing a protective coating of Zinc on Iron is known as Galvanisation .
  • Copper and Aluminium form a protective oxide layer on top and prevent the rest of the metal from corrosion. 
  • Aluminium is also used to make foils , packaging in medicine, cigarettes and food material.
  • Gold, Silver, Platinum are used to make jewellery
  • Mercury is used in thermometers.
  • Nickel, Titanium, Zirconium, Uranium are used in Nuclear Energy .


Energy Levels or Shells 

We know that an atom is made up of protons,neutrons and electrons .  

  • Protons and neutrons are present in the nucleus of an atom. However, electrons move around the nucleus in orbits
  • These orbits are called energy levels or shells .

What is the Number of Electrons in a Shell?

  • Each Energy Shell has a different number of electrons and corresponds to a different energy level.
  • The innermost shell of an atom is called the K shell. Moving outwards, the shells are named, L, M, N and so on.
  • As we move outwards from the nucleus, the energy and number of electrons in each shell increases .

Shell Name

Other Name

Max No of Electrons

K shell



L Shell



M Shell



N Shell



How is the Maximum Number of Electrons in a shell Calculated?

It is calculated by Using formula 2n 2



For K shell.n=1

So number of Electrons = 2n 2 = 2*1 2 = 2*1 = 2

Similarly for L shell.n=2

So number of Electrons = 2*n 2 = 2*2 2 = 2*4 = 8

Similarly for M shell.n=3

So number of Electrons = 2*n 2 = 2*3 2   = 2*9 = 18

Similarly for N shell.n=4

So number of Electrons = 2*n 2 = 2*4 2 = 2*16 = 32

What are Valency and Valence Electrons?

  • The electrons in the outermost shell of an atom are called valence electrons.

If no. of Valence electron <4, 

                    Valency= no. of valence electrons

            If no. of Valence electron >4,

                     Valency= 8- no. of valence electrons

            If it is a noble metal, Valency=0

For Example :

  1. Helium has 2 Electrons
  • All these are in K Shell
  • K shell is the outermost shell
  • It can hold a maximum of  2 electrons.

Hence, Helium has 2 Valence Electrons. Valency=0.

Helium atom has 2 valence electrons - Teachoo.png

  1. Sodium has 11 Electrons
  • Two of these are held in K Shell
  • 8 of these are held in L Shell 
  • Remaining 1 is held in M Shell.

Hence,  Sodium has 1 Valence Electron.

Sodium atom has 1 valence electron - Teachoo.png

  1. Chlorine has 17 Electrons.
  • Two of these are held in K Shell
  • 8 of these are held in L Shell 
  • Remaining 7 are held in M Shell.

Hence,  Chlorine has 7 Valence Electrons. Valency=1 (8-7)

Chlorine atom has 7 valence electron - Teachoo.png
Why are Valence Electrons important?

  • Valence Electrons are the electrons from the outermost shells
  • Only these electrons take part in chemical reactions .
  • Elements with a full outermost shell do not react with other elements. 
  • These elements are known as Noble/Inert gases. 

For Example,

  • Helium has 2 Elements in its outer shell.
  • K Shell can only hold 2 electrons.
  • Hence, there are no free electrons which take part in chemical reactions.
  • Valency of these elements is 0.

















What is an Ion?

  • A charged atom is called an ion. 
  • It may be positively or negatively charged.
  • A Positively charged ion is called a Cation whereas a negatively charged ion is called an anion .

How are Ions formed?

We know that an atom contains protons,neutrons and electrons.

  • Protons are positively charged, Electrons are Negatively charged and Neutrons are neutrally charged.
  • In an atom, the no of protons and electrons are equal such that an atom is neutral .
  • When an atom loses electrons , it becomes positively charged  
  • Similarly, when an atom gains electrons , it becomes negatively charged .

Formation of a cation
Formation of a Sodium ion - Teachoo.png

Formation of Magnesium Ion - Teachoo.png

Formation of an anion

Formation of Chloride Ion - Teachoo.png

Formation of Oxygen ion - Teachoo.png

Learn in your speed, with individual attention - Teachoo Maths 1-on-1 Class

Ask a doubt
Maninder Singh's photo - Co-founder, Teachoo

Made by

Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 13 years and a teacher from the past 17 years. He teaches Science, Economics, Accounting and English at Teachoo