Question

In 1804, almost a century before the nucleus was discovered, the English scientist John Dalton provided evidence for the existence of the atom. Dalton thought that atoms were the smallest particles of matter, which couldn't be divided into smaller particles. He modeled atoms with solid wooden balls. In 1897, another English scientist, named J. J. Thomson, discovered the electron. It was first subatomic particle to be identified. Because atoms are neutral in electric charge, Thomson assumed that atoms must also contain areas of positive charge to cancel out the negatively charged electrons. He thought that an atom was like a plum pudding, consisting mostly of positively charged matter with negative electrons scattered through it.

The nucleus of the atom was discovered next. It was discovered in 1911 by a scientist from New Zealand named Ernest Rutherford, who is pictured in Figure below. Through his clever research, Rutherford showed that the positive charge of an atom is confined to a tiny massive region at the center of the atom, rather than being spread evenly throughout the “pudding” of the atom as Thomson had suggested.

Question: What was the first subatomic particle found?

Answer 1

The first subatomic particle to be discovered was the electron, identified by J.J. Thomson in 1897, challenging the idea of indivisible atoms and leading to the development of the plum pudding model.

Step-by-step explanation:

The first subatomic particle discovered was the electron, which was identified by the British physicist J.J. Thomson in 1897. This discovery marked a significant breakthrough in atomic theory, as it challenged the previously held belief that atoms were indivisible and the smallest units of matter. Recognizing that the atom was electrically neutral, Thomson proposed the existence of positively charged matter to balance the negatively charged electrons within the atom, which he described with his plum pudding model. This model suggested that atoms consisted of a positively charged substance with electrons scattered throughout, similar to plums in a pudding.

The understanding of subatomic structure further advanced when Ernest Rutherford, through a series of experiments, disproved Thomson's model by discovering the atom's nucleus in 1911. Rutherford's experiments showed that the atom’s positive charge is concentrated in a tiny, dense nucleus, surrounded by electrons, thus introducing the nuclear model of the atom.

Answer 2

The Electron found by J.J Thompson