Lakshmi Raveendran

Physical Science

Reg.NO. 13982009

KUCTE, Kulakkada

POWER POINT PRESENTATION

Strcture of an atom

o All matter is made up of small particles called atoms.

o Atom is the smallest particle which can engage in a chemical reaction.

o All the atoms of an element have the same properties.

o Atoms of different elements have different characters.

o atoms can neither be created nor destroyed.

o Atoms are indivisivble.

POSTULATES OF DALTON ON AN ATOM

J.J. Thompson invented electron by discharge tube experiment

o Electrons carrying negative

charge.

o Mass of an electron is

1/1837 of themes of the

smallest atom - hydrogen

DISCHARGE TUBE EXPERIMENT

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Ernest Rutherford invented nucleus by Gold Foil

experiment

GOLD FOIL EXPERIMENT

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gold foil

beam ofalpha particles

undeflected particles

deflected particle

· Atom has a central part called nucleus.· Nucleus has positive charge· The mass of atom is concentrated in the nucleus.

· Electrons are distributed in the space around the

nucleus.

RUTHERFORD’S ATOM MODEL Rutherford’s atom

model is similar to that of the Solar System

BOHR MODEL In Neil’s Bohr atom

model each of the orbit is

a specific energy level.

The energy levels 1, 2, 3,

4 and 5 are represented

by the letters K, L, M, N,

and O respectively.

These energy levels are

known as shells

Bohr Model of Hydrogen atom

Bohr Model of Carbon atom

Bohr Model of Sodium atom

Bohr Model of Chlorine atom

Number of Protons in an atom is the atomic

number of the elements.

Mass Number is the total number of protons

and neutrons.

The maximum number of electrons that a shell

can contain can found out using the formula‘2 ’