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Atomic Models - Early Atomic Theory

atoms particles element chemical

Atomic models have their beginnings in the early atomic theory. The law of conservation of mass, the law of definite proportions, and the law of multiple proportions, provided models for the behavior of chemical reactions, but the laws could not be explained. In 1808, John Dalton (1766–1844) proposed his atomic theory, which served as an explanation for these phenomena. His theory consists of five postulates. The first postulate states that all matter is composed of atoms. Second, the atoms of a given element are all exactly the same in structure and properties. Third, atoms cannot be further divided, created, nor destroyed. Fourth, atoms of different elements combine to form compounds. Lastly, chemical reactions involve the combination, separation, and rearrangement of atoms. These five postulates not only explained the laws of conservation of mass, definite proportions, and multiple proportions, but also served as the basis for the study and development of various atomic models.

Not all of Dalton's atomic theory has stood the test of time. The evolution of the atomic model has led to the discovery that atoms are divisible into smaller particles, and that not all atoms of a given element are exactly the same. In the late 1800s, scientists discovered that atoms are composed of three subatomic particles, called protons, neutrons, and electrons. The protons and neutrons are located in a central region of the atom called the nucleus, and the electrons occupy the space surrounding the nucleus. The number and arrangement of each of these particles within the atom determine the chemical properties of the element. Atoms of the same element can differ in the number of neutrons (called isotopes) and also in the number of electrons (called ions). The number of protons is what determines the chemical identity of the element. The discovery of these subatomic particles, along with Dalton's atomic theory, set in motion the development of several atomic models. Advances in modern physics allowed scientists to find a large number of subatomic particles, including the quarks that are the fundamental subatomic particles that form protons and neutrons.


Atomic Models - Discovery Of The Electron [next]

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almost 10 years ago

dalton just thought that an atom just a particle. he didnt think that there would be subatomic particles or anything. the gold foil experiment was by rutherford (from england) which proved that there was a nucleus

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over 9 years ago

ummm can u please give me THE DATA FROM DALTONS EXPERIMENT THAT WAS LED TO THAT MODEL AND INFORMATION HOW DID DALTON'S MODEL WAS CORRECT

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over 9 years ago

well, can you please give me concrete models and illustrations made by the scientists. that will make life easier for us. thanks! :D

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over 9 years ago

could you please give me a list of the 20 most important discoveries about the atom.
and perhaps accurate information on those discoveries.

if not all this then just the names of the discoverers.
thankyou ever so much

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over 10 years ago

did john dalton think that atoms are just empty space or do a gold foil experiment or is from english

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about 6 years ago

the atomic theory was proposed in 1803 not 1808 people!