Molecules

“Molecule is an electrically neutral group of two or more atom chemically bonded together by means of attractive force.”

OR

“A molecules is group of two or more atom which are held together strongly  by some kind of attractive forces.”

  • Such an attractive force holding the atoms together is called chemical bond.
  • A molecules is an smallest particles of an elements or compound which can exist in freely under ordinary and show all the properties of that substance.
  • For example water molecules show all the properties of water.

H2O Molecule

Type of molecules:

There are two types of molecules.

1) Molecules of compound.

2) Molecules of elements.

1) Molecules of compound:

The Molecules of compound contains different types of atoms chemically combine together. Or

Molecules of compound means two or more different elements combine together in a definite proportion by mass to form compound or substance.

For example:

  • CH4
  • NH3
  • H2 O etc.

  • Diatomic Molecules:

When two atom of different elements combine together by chemically attractive forces in a fixed proportion called diatomic molecules.

Example Hydrogen chloride(HCl),  carbon monoxide (CO) etc.

  • Tri atomic molecules:
  • When three atom of different elements combine together by chemically attractive forces in a fixed proportion called Triatomic molecules.

Example : H2O, CO2 ,  SO2  etc.

  • Tetratomic molecules:
  • When four atom of different elements combine together by chemically attractive forces in a fixed proportion called Tetratomic molecules.

Example :hydrogen peroxide ( H2O2), ammonia (NH3 ) etc.

2) Molecules of elements:

Molecules of elements means one  two or more atom of the same elements combine together.

  • Depending upon whether the molecules contain one two three four etc. atom are called monoatomic, diatomic, triatomic, and tetratomic

Monoatomic Molecules:

  • Elements consist of single atom.
  • Nobel gas like helium, Neon, Argon etc. Exist in single atom that is He, Ne,Ar, etc.
  • Hence their molecules are monoatomic.
  • The symbols for their molecules are same.

Diatomic Molecules:

  • When two atom of same elements combine together by chemically attractive forces called diatomic molecules.
  • Example molecules of hydrogen , two atom of hydrogen exist together its molecule is, H2, that is it is diatomic molecule.
  • Molecule of hydrogen can not be represented as 2H.
  • Because this will represent as two atom of Hydrogen (2H) not a molecule.
  • Same applies to other molecule that is N2, O2,

So there atomicity is two.

Tri atomic molecules:

  • When three atom of same elements combine together by chemically attractive forces called triatomic molecules.
  • For example in a molecule of ozone three atom of oxygen exist together same or one species.
  • So there atomicity is three.

Example : O3,

OZONE  (O3)

Tetratomic molecules:

  • When four atom of same elements combine together by chemically attractive forces called tetratomic molecules.
  • A very common example of tetratomic molecule is P4 ,  that is phosphorus molecule.
  • So there atomicity are four.

Atomicity:

The number of atom present in one molecule of the substance are called atomicity.

Phosphorus P4

Question Answer:

1) What is molecules?

Answer:  A molecules is group of two or more atom which are held together strongly  by some kind of attractive forces.”

2) What is molecules of compound?

Answer: The  Molecules of compound contains different types of atoms chemically combine together.

For example:

  • CH4
  • NH3
  • H2O etc.

3) What is diatomic molecules?

Answer:•When two atom of same elements combine together by chemically attractive forces called diatomic molecules.

  • Example molecules of hydrogen , two atom of hydrogen exist together its molecule is, H2, that is it is diatomic molecule.
  • Molecule of hydrogen can not be represented as 2H.
  • Because this will represent as two atom of Hydrogen (2H) not a molecule.
  • Same applies to other molecule that is N2, O2, etc.

4) What is atomicity?

Answer: The number of atom present in one molecule of the substance are called atomicity.


Leave a Reply

Your email address will not be published. Required fields are marked *

five × 4 =