Atoms And Molecules

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• Questions
• Summary

The following two laws of the chemical combination were established by Lavoisier and Joseph L. Proust.

In a chemical reaction, the total mass of product is equal to the total mass of the reactant.
"In other words, mass neither be created nor be destroyed in a chemical reaction."

"In a chemical substance, the elements are always present in definite proportions by mass”.

Postulates of Dalton’s atomic theory

• All matter is made of very tiny particles called atoms.
• Atoms are indivisible particles, which cannot be created or destroyed in a chemical reaction.
• Atoms of a given element are identical in mass and chemical properties.
• Atoms of different elements have different masses and chemical properties.
• Atoms combine in the ratio of small whole numbers to form compounds.
• The relative number and kinds of atoms are constant in a given compound.