Question

Explain the Thomson's Atomic Model

Answer 1

J J Thomson's model of the atom:

• J J Thomson was the first to propose a detailed model of the atom.
• Using a cathode ray scope, Thomson determined that all matter, whatever its source, contains particles of the same kind that are much less massive than the atoms of which they form a part. he called them ‘corpuscles’.(they are now called electrons).
• By applying an improved vacuum technique, Thomson proved that these rays were composed of the same particles, regardless of what kind of gas is taken in the discharge tube or what metals were used as conductors.
• From these ideas, Thomson developed the idea that atoms are made of negative electrons embedded in a gel of positive charge. this model is known as the Plum pudding model or watermelon model.

• This model assumed that mass of the atom is evenly spread over the entire atom.
• This model could explain the electrical neutrality of atoms but failed to explain the observation of Rutherford's $\alpha$particle scattering experiment.