Dalton atom theory

Keeping in the view of chemical combination and the work of British chemist john Dalton Provided the basic theory about nature of matter known as Dalton’ s atomic theory.

The basic postulate of Dalton’s atomic theory are following.

Postulate:

  • All matter is made up of tiny particles called atom which participated in chemical reactions.

For example,

  • Atom are individual particles which can not be created or destroy in a chemical reactions

In a chemical reaction atom combine to form new unit. . Existing one can not be destroyed and new one can not be formed.

For example;

Only arrangement of atom occur. No new atom formation.

  • Atom of given elements are identical in mass and chemical properties.

Both the atom have the same mass that is 16u and 16u chemical properties.

  • Atom of different elements have different masses and different chemical properties.

Both have different masses and chemical properties.

  • Atom combine in the ratio of small whole number to form compound.

Ratio combination of atom is always whole number.

H2O  :  2:1

CO2:  1:2

HCl  :  1:1

  • The relative number and kind of atom are constant in a given compound.

H2O  :  2 atom hydrogen

1 atom oxygen

CO2:  1 atom carbon

2 atom oxygen

HCl  :  1 atom hydrogen

1 atom chlorine.

Merits of Dalton’s atomic theory:

  • Dalton’s atomic theory provide us a conceptual picture of matter.
  • Atom are the basic building blocks of the matter.
  • They are smallest unit of an elements that can combine with other elements in a chemical reactions .
  • In compound atom of two or more elements combine in a definite arrangements .
  • The postulate of Dalton’s atomic theory “ atom can neither be created nor destroyed “. Was the result of law of conservation of mass.
  • The postulate of Dalton’s atomic theory  that the elements consist of  atom having fixed mass. And that number and kind of atom in a given compound in a fixed ratio  was the results of law of constant proportion.

Limitations/ Drawbacks of Dalton’s atomic theory:

  • Atom is no longer considered as the smallest individual masses because it consists of sub atomic particles protons, neutron, and electrons.
  • Atom of the same elements may have different masses.
  • Atom of the same elements may have same masses.
  • Substance made up of same kind of atom may have different properties.

 

Question answer:

1) Write the postulate of Dalton’s atomic theory?

Answer: Postulate of Dalton’s atomic theory are following.

  • All matter is made up of tiny particles called atom which participated in chemical reactions.
  • Atom are individual particles which can not be created or destroy in a chemical reactions.In a chemical reaction atom combine to form new unit. . Existing one can not be destroyed and new one can not be formed.
  • Atom of given elements are identical in mass and chemical properties.
  • Atom of different elements have different masses and different chemical properties.
  • Atom combine in the ratio of small whole number to form compound.
  • The relative number and kind of atom are constant in a given compound.

2) Write down the merits of Dalton’s atomic theory?

Answer:•  Dalton’s atomic theory provide us a conceptual picture of matter.

  • Atom are the basic building blocks of the matter.
  • They are smallest unit of an elements that can combine with other elements in a chemical reactions .
  • In compound atom of two or more elements combine in a definite arrangements .
  • The postulate of Dalton’s atomic theory “ atom can neither be created nor destroyed “. Was the result of law of conservation of mass.
  • The postulate of Dalton’s atomic theory that the elements consist of  atom having fixed mass. And that number and kind of atom in a given compound in a fixed ratio  was the results of law of constant proportion.

3) Write limitations of Dalton’s atomic theory?

Answer: • Atom is no longer considered as the smallest individual masses because it consists of sub atomic particles protons, neutron, and electrons.

  • Atom of the same elements may have different masses.
  • Atom of the same elements may have same masses.
  • Substance made up of same kind of atom may have different properties.

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