Basic unit of Chemistry – Atom

Smallest units of a matter – Atom

The first atom model was created by – Neils Bohar

The most accepted model of the atom Bohar model

Atom was derived from a greek word ‘Atoms’ (means indivisible)

Atom was discovered by John Dalton

Law of Multiple Proportion was put forward by – John Dalton

Law of conservation of Mass – Antoine Lavoisier

Law of difinite proportion – Joseph Proust

Atomic theory – John Dalton

Planetary Model of Atom – Rutherford

Wave mechanics model – Max Planck

The term ‘atom’ was coined by – Ostwald

The fundamental particles of an atom Proton, Electron and Neutron

The central part of an atom – Nucleus

The sub atomic particles of nucleus – Protons Neutrons

Heaviest sub atomic particle – Neutron

Lightest sub atomic particle – Electron

Moving particle of an atom – Electron

The charge of an electron is – Negative

Protons and Neutrons are collectively known as – Nucleons

Chemical property of a substance is determined by – Electrons

The smallest atom – Helium (He)

The simplest Atom – Hydrogen(H)

Biggest known atom – Francium(Fr)

The unit of measuring mass of an atom – Atomic Mass unit(AMU)

1 atomic mass unit is equal to 1.6605 x 10-27 Kg

The element used to find amu – Carbon -12


Electron is discovered by – J.J. Thomson

The name Electron was proposed by –  Stoney

Charge of an electron 1.6 x 10-19C (determined by Millikan)

Mass of electron 9.1 x 10-31 kg

Dual nature of electron Louis-de-broglie


Proton was discovered by Ernest Rutherford

The identity card of an element Proton

The mass of a proton is 1.672 x 10-27kg

The theory of Proton was presented by William Prout


Neutron was discovered by  – James Chadwick in 1932

The heaviest fundamental particle of an atom Neutron

The least stable particle Neutron

Neutrons are bound very tightly Chargeless particle of an atom Neutron


The atom without neutron Protium (Isotope of Hydrogen)

Atomic Number – It is the number of protons in the nucleus of an atom

Atomic number denoted by the alphabet – Z

Mass Number – The total number of protons and neutrons present in the nucleus of an atom

Mass Number is denoted by – A

Antiparticle of the neutron with the same mass of neutron – Anti neutron

Antiparticle of the neutron with the same mass of proton – Anti proton

Nuclear particle with the mass of an electron but opposite change – Positron 

The combining capacity of one atom to another Valency

Atom is bigger than its nucleus 105 times

Electrons move in a circular path called Orbit

The maximum number of elements in an Orbit is 2

The Orbit followed by a moving electrons around the nucleus of an atom Shell

The maximum number of electrons in a shell 2n2(n=Number of shell)

Atomic theory – John Dalton

Uncertainty principle – Werner Heisenberg.

Structure of Atom – Niels Bohar

Plum Pudding Model – J.J. Thomson

Wave Mechanics Model – Max Planck

Electron (-ve charge) – J.J. Thomson

Proton (+ve charge) – Ernest Rutherford

Neutron(No charge)- James Chadwick

Nucleus (+ve charge) – Ernest Rutherford

Positron (+ve charge) – Carl Anderson

Antineutron (No charge) – Bruce Cork