Question

class 9 science chapter 3 atoms and molecules notes ​

Answer 1

Atoms and Molecules notes:

Introduction:

• Thought of distinctness of issue: Maharishi Kanad (old Indian scholar) proposed that if we continue partitioning the matter, a state will come when no further division is conceivable that state is called 'parmanu'.
• Naming of a definitive molecule: Democritus and Leucippus named this extreme molecule atom.
• Chemical laws: A.L Lavoisier gave two laws of chemical combination. Peruse further in atoms and particles notes for the definite matter.

Law of Chemical Combination:

There are two laws of chemical combination given by Lavoisier and L.Proust as follows:

• Law of preservation of mass: During a chemical response mass cannot be made nor obliterated. As, A + B → C + D Here, Mass of An and B = Mass of C and D
• Law of consistent proportion: The components in a chemical substance are generally present in distinct proportions by mass.

Atomic Theories:

• Numerous Scientists engaged in investigating definitive particles and attempted to clarify the two chemical laws.
• John Dalton was the first among them who approached to give his hypothesis.
• Atoms and particles notes thought about every single atomic reality.
• As indicated by him all matter whether it is a component, a compound or a combination comprises of moment imperceptible particles called 'atoms'.

Atoms:

• Atoms are the structure squares of the issue.
• The littlest molecule of a substance that partakes in a chemical response is supposed to be atoms.
• The sweep of a hydrogen atom is 10-10m.
• Range of atom is estimated in nanometer. (1m = 10-9 m)

Molecules:

• The littlest molecule of a component or a compound that is equipped for an autonomous presence and shows every one of the properties of that substance is supposed to be Molecules.
• Additionally we say, it is a gathering of at least two atoms that are chemically reinforced together or firmly kept intact by alluring powers.
• Either atom of a similar component or various components can combine to shape molecules.
• The molecules of a component comprise the same sort of atoms.