9th science

Atoms and Molecules

Atoms:

On the basis of Dalton’s Atomic Theory "The smallest particles of matter are called Atoms".

Characteristics of atoms:

  • Atom is the smallest particle of matter.
  • All elements are made of tiny particles called atom.

  • Atoms are very small in size and cannot be seen through naked eyes.
  • Atom does not exist in free-state in nature. But atom takes part in a chemical reaction.
  • The properties of a matter depend upon the characteristics of atoms.
  • Atoms are the building block of an element similar to a brick which combine together to make a building.
  • The size of atoms is indicated by its radius.
  • In ancient time atoms was considered indivisible.

Symbols of Atoms of Elements

For convenience elements are represented by unique symbols. For example: Hydrogen is represented by ‘H’.
Oxygen is represented ‘O’.
Nitrogen is represented by ‘N’.
Iron is represented by ‘Fe’.

For these marvelous work Berzilius, together with John Dalton, Antoine Lavoisier, and Robert Boyle is considered as the Father of Modern Chemistry.


Name and Symbol of some elements

ElementSymbol
HydrogenH
HeliumHe
LithiumLi
BerylliumBe
BoronB
CarbonC
NitrogenN
OxygenO
FluorineF
SodiumNa
MagnesiumMg
AluminiumAl
PhosphorousP
SulphurS
PotassiumK
CalciumCa

Symbol of many elements are taken from their English name, while symbol of many elements are taken from their Greek or Latin names.

Symbol of some element which are derived from their Latin name

English nameSymbolLatin name
SodiumNaNatrium
PotassiumKKalium
IronFeFerrum
CopperCuCuprum
SilverAgArgentum
GoldAuAurum
MecuryHgHydragyrum
LeadPbPlumbum
TinSnStannum

Several elements are named after the place where they discovered'

Example ‘Copper is discovered in Cyprus. Thus, it got its name similar to Cyprus.

Some elements are named after their colour

Example ‘Gold’ which means yellow.