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).
