Question

Class 9th
Chemistry 3:- ATOMS AND MOLECULES
please give me notes
(Don't write irrelevant answer) ​

Answer 1

Answer:

The basic notes of the chapter Atoms and Molecules are as follows :-

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Atoms and Molecules

★ Basic Concept :-

This chapter is related about the different parts in the atom and molecules and their further divisions. Also topics like compounds, elements, Dalton's Atomic Theory, Rutherford's model, etc. are discussed.

• Atoms :-

These are smallest in individual particles of a substance. They consists of three parts Protons, Neutrons and Electrons.

Protons are the positive charged particles in the atom that lie in the nucleus.Electrons are the negative charged particles in the atom that revolve in orbits in the the atoms.Neutrons are the neutral charged particles which credit for the mass of the atom.Since, the number of electrons are equal to the number of protons, they cancel out each other's charge and thus make the electron stable in the ground state.

• Molecules :-

These are the group of two or more atoms of an element. Some elements exist in the form of molecules like Hydrogen, Nitrogen, Oxygen, etc.

Elements:-

These are the substance which consists of one type of particles.

• Compounds :-

These are the group of atoms formed when atoms of two or more elements come together to form bonds.

Pure substances:-

These are substances that have fixed composition and constituents of pure substances cannot be seperated by simple physical methods.

• Mixture :

These are substances that do not have fixed composition and constituents of mixtures can be seperated by simple physical methods.

• Matter ::

Anything or any substance which has mass and occupies space is called matter.

• Homogenous Mixtures :

In this type of mixture, the components completely mix with each other and composition is uniform throughout.

• Heterogeneous Mixtures :

In this type of mixture, the components don't completely mix with each other and composition is not uniform throughout.

• Rutherford's Scattering Experiment

In this, Rutherford's Scattering Experiment a beam of α particles were shot on thin - gold film which showed that the beams were deflected at some places which showed the presence of electrons at those places which were the cause of deflection.

• Atomic Number :-

It is the number of protons or number of neutrons in the each atom of an element.

• Mass Number :-

It is the sum of number of protons (Z) and number of neutrons.