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john dalton
He developed modern atomic theory, and he researched colour blindness. Tje atomic theory which stated that all matter was composed of atoms, atoms of a given element possess unique characteristics and weight, and three types of atoms exist: simple (elements), compound (simple molecules), and complex (complex molecules). Dalton's theory was presented in New System of Chemical Philosophy -
dalton's model
This model explains that all matter is composed of atoms and
Dalton proposed his model electrons and the nucleus were unknown. -
william crooke
he was a British chemist and he invented the Crookes tube & Crookes radiometer. He invented many devices to study the behaviour of cathode rays, In 1861 he discovered thallium. During his studies of thallium, Crookes discovered the principle of the Crookes radiometer, a device that converts light radiation into rotary motion. -
J.J Thomson
In 1897, Thomson showed that cathode rays were composed of a previously unknown negatively charged particle, and thus it led to the discovery of the electron. He also found the evidence for isotopes of a stable element in 1913 and he invented the mass spectrometer. He also did the conduction of electricity in gases. -
Plum pudding model
The atom is composed of electrons surrounded by positive charge to balance the electrons' negative charges. -
Earnest Rutherford
Rutherford who was a New Zealand physicist discovered the atomic nucleus in 1912. and he made Rutherford model.
He made a expreiment called "the Gold Foil experiment" to study how alpha particles, with a 2+ charge, interact with a piece of very thin gold foil. He found that most of the alpha particles passed sraight through the foil which means the electrons move about the nucleus, not in a fixed location. -
rutherford model
Ernest Rutherford developed the planetary model of the atom which put all the protons in the nucleus and the electrons orbited around the nucleus like planets around the sun. -
Niels Bohr
Niels Bohr was a Danish physicist who made foundational contributions to understanding atomic structure and quantum mechanics. Also he mde Bohr model -
Bohr Model
Introduced by Niels Bohr,
depicts the atom as small positively charged nucleus surrounded by electrons that travel in circular orbits. -
Quantum mechanical model
The quantum mechanical model is based on quantum theory, which says matter also has properties associated with waves. According to quantum theory, it’s impossible to know the exact position and momentum of an electron at the same time. The quantum mechanical model shows that electrons don’t have set orbital but are in random motion confined within the areas of electron probability confined within the areas of electron probability distribution. -
James Chadwick
Rutherford predicted that another kind of particle must be present in the nucleus along with the proton. He predicted this because if there were only positively charged protons in the nucleus, then it should break into bits because of the repulsive forces between the like-charged protons. To make sure that the atom stays electrically neutral, this particle would have to be neutral itself. In 1932 James Chadwick discovered the neutron and measured its mass.
