J.J. Thomson
Explanation
The scientific understanding of matter evolved from the concept of indivisible particles to the realization that atoms have an internal structure composed of subatomic particles. Various scientists proposed models to describe this arrangement chronologically.- J.J. Thomson (Correct): In 1898, J.J. Thomson proposed the first specific model for the structure of an atom, often referred to as the "Plum Pudding" or "Watermelon" model. He postulated that an atom consists of a positively charged sphere with negatively charged electrons embedded within it, similar to seeds in a watermelon or raisins in a pudding.
- John Dalton: In 1808, John Dalton proposed the Atomic Theory, which stated that the atom is the ultimate, indivisible particle of matter. Since he considered the atom indivisible, he did not propose a model for its internal structure.
- E. Rutherford: Ernest Rutherford proposed the Nuclear Model of the atom in 1911. This model, based on the alpha-particle scattering experiment, identified the presence of a dense, positively charged nucleus. It was proposed after Thomson's model.
- Neils Bohr: Neils Bohr proposed his atomic model in 1913. He improved upon Rutherford’s model by introducing the concept of discrete, stable energy orbits (shells) for electrons.
Key Takeaway: While John Dalton is credited with the first atomic theory, J.J. Thomson is credited with proposing the first model describing the internal structure of an atom following the discovery of the electron.