Chemistry > Structure of Atom > 5.0 Atomic Number and Mass Number and It's Relation
Structure of Atom
1.0 Introduction
2.0 Cathode Ray Discharge Tube
3.0 Thomson Model of Atom
4.0 Rutherford Model of Atom
5.0 Atomic Number and Mass Number and It's Relation
6.0 Planck's Quantum Theory
7.0 Bohr’s Atomic Model
8.0 Dual Behaviour of Matter
9.0 Heisenberg Uncertainity Principle
10.0 Photoelectric Effect
11.0 Atomic Spectra
12.0 Quantum Mechanical Model of Atom
13.0 Quantum Number
14.0 Electronic Configuration of Elements
14.1 Aufbau (or building up) Principle
14.2 Pauli’s Exclusion Principle
14.3 Hund’s Rule
14.4 Stability of Completely Filled and Half Filled Subshells
5.1 Isotopes
14.2 Pauli’s Exclusion Principle
14.3 Hund’s Rule
14.4 Stability of Completely Filled and Half Filled Subshells
- Atoms of the same element that have different masses
- All elements of the same element have the same number of protons, but may vary in the number of neutrons
- Although isotopes have different masses, they do not differ significantly in their chemical behavior
Example: Considering of hydrogen atom again, 99.985% of hydrogen atoms contain only one proton. This isotope is called protium(${}_1^1H$). Rest of the percentage of hydrogen atom contains two other isotopes, the one containing 1 proton and 1 neutron is called deuterium (${}_1^2D$, 0.015%) and the other one possessing 1 proton and 2 neutrons is called tritium (${}_1^3T$).
Why isotopes have similar chemical properties?
Chemical properties of atoms are controlled by the number of electrons, which are determined by the number of protons in the nucleus. Number of neutrons present in the nucleus have very little effect on the chemical properties of an element. Therefore, all the isotopes of a given element show same chemical behaviour.
