Thomson's model of an atom
#Thomsonsmodel
#plumpuddingmodel
#atomicmodel
#chemistry
#Atom is the building block of #matter.
All the things around us, our food, clothes and even we are made of these tiny atoms.
The word ‘atom’ has its origin from the Greek word ‘#atomos' means #indivisible or which cannot be cut.
For many years it was believed so.
But static electricity and conduction of electricity by certain substances indicated that atoms are not indivisible. They contain something which has charge.
This led to the discovery of sub-atomic particles namely
#electrons which are negatively charged.
#protons which are positively charged and
#neutrons, the neutral particles.
After the discovery of these three , the challenge before the scientists was
To explain:
1) the stability of the atom.
2)The distribution of these charged particles in the atom.
In 1898 J .J. #Thomson proposed an atomic model called plum pudding or raisin pudding or it is also called watermelon model.
According to this model, an atom is spherical in shape having uniform distribution of positive charge.Thus the red portion of the watermelon represents the positive charge of the atom.
The seeds in the watermelon or the raisins in the pudding are like the negatively charged #electrons embedded into the positive charge.
The magnitude of negative and positive charges is equal. So the atom as a whole is electrically neutral.
Drawback of this model was although this model explained the neutrality of the atom, it could not explain the results of later experiments.
Keeping in mind, Thomson's model, #Rutherford and his students performed the #alpha particle scattering experiment.
However, the observations of the experiments proved that Thomsosn's plum pudding model is incorrect.
Thus this experiment was a turning point in describing the structure of atom.
Image courtesy:
#Rutherford: The original uploader was Sadi Carnot at English Wikipedia. • CC-BY-SA-3.0
#Thomson:https://en.m.wikipedia.org/wiki/J._J....
#Geiger: https://en.m.wikipedia.org/wiki/Geige...
#Marsden: https://upload.wikimedia.org/wikipedi...