Material Science and Metallurgy

1

Atomic Structure

1.1 INTRODUCTION

Up to the end of nineteenth century even the prominent scientists doubted the presence of an atom, but in 1899, J.J. Thomson proposed the existence of an atom and found that electrons are constituents of all matter. Now a days everybody realizes the existence of atoms, which are the building blocks of all the materials. Today, even an individual atom can be identified and photographed; through the light an atom emits. Atoms are stable and exist for billions of years without any change. They can combine together to form solids and can interact with other atoms to make compounds. Atoms can also emit or absorb light.

In an atom, there is a nucleus containing protons (positively charged particles) and neutrons ...