What is an atom? What is molecule? What are Ions?

What is an atom?

An atom is simplest and fundamental unit of matter that takes place in the chemical reactions.

What is molecule?

A molecule is a combination of two or more atom.

Even though atom is a fundamental unit what is a necessary for molecules?

Most of the atoms cannot exist independently, so they occur as combinations of two or more atom (molecules) to exist in the atmosphere.

What are Ions?

Ions are the charged particles. They are divided in two i) Cation
                                                                                        ii) Anion

Cation:

The positively charged particles are called cation.They are formed when the no. of proton are greater than the no. of electron in an atom.

1. Proton are positively charged.
2. Electrons are negatively charged.
3. Neutron is uncharged.

P > E

Ex: P = 4, E =3, N =3

P = 4 x 1       =    4
E = 3 x -1     =   -3
N = 3 x 0      =    0
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                    =   + 1
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So it is positively charged.

Anion:

The negatively charged particles are called anion.They are formed when the no. of proton are lesser than the no. of electron in an atom.

1. Proton are positively charged.
2. Electrons are negatively charged.
3. Neutron is uncharged.

P < E

Ex: P = 4, E =5, N = 4

P = 4 x 1       =    4
E = 5 x -1     =   -5
N = 4 x 0      =    0
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                    =   - 1
------------------------------

So it is negatively charged.