The theory that
metter was made from small indivisible particles called
atoms date back to some five centuries B.C to
democritos and a century B.C to a roman
poet leukiphos.
This theory was put on sound scientific basis by jonh Dalton in 1808.
Today it is well established that atoms are complex organizations of metter and energy . Many
particles have been discovered within the atoms.
These sub atomic particles include electron,
proton, neutron , and several types of mesons
and hyprons etc. since electron, proton and neutron in the atom play a
major role in determining the chemical
and physical properties of metter.
we will, therefore, restrict ourselves to the study of these particles.
edvidence for the presence of electron, proton and neutron in the atom is derived through many experiments such as:
- Faraday's experiment indicates the existence of electrons.
- crooke's tube experiments show the presence of electron and proton in the atoms.
- Radioactivity further comfirms the presence of electrons and proton.
- chadwick experiments show the presence of neutron.
- Spectrosocpic experiments reveal the electronic structure of atoms.
These are discussed one by one
