PROJECT NAME
STRUCTURE OF ATOM
NAME: TANUJ SAINI
CLASS: 9 TH A
ROLL NO.: 26
SUBMITTED BY : TANUJ SAINI
SUBMITTED TO : MRS. GUNJAN GOYAL
 We will see many thing chair, table, wood ice in our
daily life. Any thing which occupies space and has
mass is called matter. All the matter is made up of tiny
particles and particles are made up of Atom. Atom is
the smallest part of the matter.
 Structure of Atoms:Atom is the smallest part of matter-An Atom is the
smallest particle of an element. Atom is found
impure stage.
Nucleus
Nucleus is the main part of the atom. Nucleus is made
up of two particles
1) Protons
2) Neutrons
 The existence of protons in the atoms was shown by E.
Goldstein. The proton is a positively charged particle
found in the atoms of all the element.
 Characteristics of a Proton
The two important characteristics of a proton are its mass
and charge. These are described below.
1.Mass of a Proton
The relative mass of a proton is 1u The absolute mass of a
proton is 1.6x 10.24 gram.
2. Charge of a Proton
So the absolute charge of a proton is 1.6×10*-19 coulomb of
positive charge. The relative charge of a proton is +1
The Discovery of Neutron particle by chad wick in 1932. The neutron is a
neutral particle found in the nucleus of an atom. The sub atomic
particle not present in a hydrogen atom is neutron.
Characteristics of a Neutron
The two important characteristics of a neutron are its mass and charge.
These are described below.
1.
Mass of a Neutron
The relative mass of a neutron is 1u. The absolute mass of a neutron is
1.6×10*-24 gram.
2.
Charge of a Neutron
Neutron has no charge. It is electrically neutral
EX. Atomic mass of carbon= mass of 6 proton+ mass of 6 neutron
=6×1+6×1
=12u
 The existence of electrons in an atom was shown by J. J.
Thomson in 1897. Cathode rays consist of small, negatively
charged particles called electrons. The electron is a negatively
charged particle found in the atoms of all the element.
Characteristics of an electron
The two important characteristics of an electron are its mass and
charge. These are described below.
1.
Mass of an electron
The relative mass of an electron is 1/1840 u the absolute mass
of an electron is , how ever 9 ×10*-28 gram.
2. Charge of an electron
The absolute charge on an electron is 1.6 ×10*-19
Coulomb of negative charge. The relative charge of an electron is,1