PARTICLES OF ATOMS

FUNDAMENTAL PARTICLES OF ATOMS

Particles in nucleus are called nucleons which are madeup of proton and neutrons

Nucleus is surrounded by a cloud of electron

Relative atomic mass A

A single atom is two small and light and cannot weighed directly

The best way to determine the mass of a single atom is to compare its mass to the mass of another atoms of an element that is used

Hydrogen was the first element to be chosen as the standard for comparing masses because thehydrogen is the lightest atom with a mass 1.0 a.m.u. (atomic mass unit)



MOLE CONCEPT AND AVOGADRO CONSTANT

One mole = 12 grams of carbon-12

One mole contains 6.02 x 10

23numbers of atoms. This is known as Avogadro Constant

Molar mass = Relative atomic massBUT, Relative atomic mass does not have any units, but molar mass have unit, g mol
-1

Volume occupied by 1 mol of any gas is called the molar volume

Isotopes

--Isotopes are elements which have same number of proton but different number on nucleon and neutron.
--Isotopes have different physical properties such as melting point, boiling point, density and rateof diffusion
--Some isotopes are unstable. These unstable isotopes are known as radioactive isotopes(Radioisotopes).