Atoms, Molecules & Ions

In this theory, definitions of atoms, molecules, monoatomic, diatomic, ions, anion and cations are given.

Atoms, Molecules and Ions

Atoms

• The smallest particle of any object is called as atoms. 
• Every object is made of atoms. 
• However, the entire world is made of matters. 
• The atoms are very small and they measured in the nanometers. 
• The relative size of hydrogen atom is 10 ^{– 10} m.
• 1 nano meter = 10 ^{– 9} m

Molecule

• It is group of two or more atoms which are chemically bonded together, tightly together by attractive forces. 
• It is defined as the smallest particle of an element / compound and show all properties of substance. 
• The atoms of same element or different elements can join together to form molecules.

Monoatomic

• The molecules of element is made up of only one atom of that element, example argon ( Ar ) and Helium ( He ).

Argon	Ar
Helium	He
Sodium	Na
Iron	Fe
Aluminum	Al
Copper	Cu

 

Diatomic

• The molecules of element is made up of two atom of that element. 
• The molecule of oxygen consists of two atoms of oxygen. 
• Examples of Diatomic

Oxygen	O2
Nitrogen	N2
Hydrogen	H2
Chlorine gas	Cl2

 

Ions

• The charged species ( total number of electrons is not equal to total number of protons ) are known as ions. 
• The metals and non metals contain charged species. 
• An ion is charged particle and can be positively or negatively charged.

Anion

• A negative charged ion is called as Anion.

Cation

• A positive charged ion is called as Cation. 
• The ion may consist of single charged atom or group of atoms which have net charge of them.

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