1.0 Introduction

  Structure of Atom

• The word 'atom' has been derived from the Greek word'a-tomio' which means 'non-divisible'.
• Many theories were proposed to define the structure of atom.
• The first atomic theory was proposed by John Dalton in 1808, called as Dalton's atomic theory.
• This theory stated that atom is the smallest particle of matter. Further studies showed that atoms can be divided into sub-atomic particles like electron, proton, neutron.