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When you break any material into its smallest piece without changing its chemical properties it is known as Molecule.

The material may be made up of one or more simpler substances called Elements.

A molecule of Water is made up of 3 atoms: H, H, and O (H2O).

A molecule of Carbon dioxide is made up of 3 atoms: C, O, and O. (CO2).

A molecule of Oxygen is made up of 2 atoms of the same element: O and O (O2).

Similarly, molecules of Protein are made up of a few to hundreds of atoms different elements.

So, if you further split the molecule of any material its chemical properties changes but it breaks into tiniest particles known as Atoms,

-atoms of the elements the material is made up of.

And if you break atom it becomes atom bomb! You don't want to do that.

Thus, atom is, so called, the tiniest unit of element (matter) that has all the properties of that matter or element.

Element is a substance that cannot be split into a simpler substance.

Scientists have found about 118 different kinds of elements or atoms so far.

There may be many more but we do not know about them now. Some of you may find them in future.

Scientists have given every atom a Name, Symbol and a number called Atomic Number.

Every atom also has weight called Atomic Weight and a Charge +, -, or 0.

Scientists further have arranged these atoms into a descent table according to their number and other properties.

This table is called Periodic Table of the Elements.

Dmitry Mendeleev produced the first periodic table in 1869.

You can see the periodic table below.

For further details refer to the text books.

Periodic Table of the Elements

H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac Rf Ha Sg Ns Hs Mt 110 111 112 114 116 118
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
Name Number Weight
Melts Boils


Alkali metals

Alkali earth metals
Transitional metals Other metals
Nonmetals Noble gases
Lanthanide series (rare earth elements) Actinide series