Definition of Atomic

The term atom comes from Greek, there is atomos which means it can't be cut up. The definition of atoms first from Greece is by Leucippus and Democritus at the beginning of the year 500SM - 400SM that any material can be for to the smallest (atomic).

And the definition of an atom, according to the chemical class X is particles that make up the smallest of all the items that can not be divided.

The definition of an atom the second by Aristoteles in the 384SM and 332SM that atoms is the material can be divided over and over again into smaller portions.

We may still be confused with atoms in fact, then we should look first of the discovery of an atom. An atom is divided into 4, namely :
1. The Atomic Theory of Dalton (John Dalton).
2. The Atomic Theory of Thompson (J.J Thompson).
3. The Atomic Theory of Rutherford (Ernest Rutherford).
4. The Atomic Theory of Bohr (Niels Bohr).

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The Atomic Theory of J.J. Thompson

Joseph John Thompson (1903)

In the opinion of J.J. Thompson, the atom is shaped like a bun and explains that the positively charged atoms in the presence of negatively charged electrons surrounding it.

Note:
(+) = Proton
(-) = Electron

Electron discovered by J.J. Thompson through a cathode ray tube experiments. At that time, Thompson noticed that if the electric current passing through a vacuum tube, there is a kind of sparkling formed. And found that the light sparkling turn to the positive plate.

Thompson then called sparkling streams such as electrons.

Thompson's Atomic Excess:
1. Proving the existence of other negatively charged particles in the atom. Which means that the atom is not the smallest part of an element.
2. Can explain the electrical properties of atoms.
3. Can explain the existence of particles smaller than atoms called subatomic.

Thompson's Atomic Shortage:
1. Unable to explain the phenomenon of out alpha particles by a thin membrane gold-stated by Rutherford.
2. Not being able to explain the existence of the atomic nucleus.
3. Thompson's atomic model can not explain the arrangement of positive and negative charges in the atomic sphere.

A few information about atomic theory J.J. Thompson, please comment if there are deficiencies or errors of this article.

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The Atomic Theory of John Dalton

John Dalton (1808)

According to Dalton, the atom is the smallest part of a substance that can not be subdivided and shaped like a solid ball that is not hollow. Dalton's atomic theory is based on two laws, the law fixed arrangement (Prouts) and the conservation of mass (Lavoisier):

- Lavoisier = total mass of substances before the reaction is always the same as the total substance reaction products.

- Prouts = Comparison of a mass of elements in a compound will always remain.

Here's an example of a model Atom Dalton:

Dalton's Atomic Opinions:
1. Atom is the smallest piece of matter that can not be subdivided.

2. Atom has been described as a very small solid ball, an atom has identical elements and different for different elements.

3. Atoms combine to form compounds with simple comparisons and integers. As the waters of Hydrogen and Oxygen atoms.

4. A chemical reaction is merging / splitting / constituent and the back of the atom, that atom could not be destroyed / destroyed.

Dalton's Atomic Excess:
1. Can explain the laws of chemical combination.

2. Dalton was the first to recognize the difference that can be applied between a particle of an element / atoms and molecules / compounds.

Dalton's Atomic Disadvantages:
1. This theory has failed to explain the existence of allotropes. Differences in the nature of charcoal, graphite and diamond are not able to be explained because they are made up of the same atoms, namely Carbon.

2. Atoms of the same element that is the same in all respects. This statement is incorrect, because the atoms of different elements have different mass numbers are called isotopes

37Cl → 35Cl

3. John Dalton said the atoms of different elements. It is proven wrong in a particular case.

4. Atoms of different elements have joined the simple number ratios to form compounds. This was not seen in the complex compounds eg sugar (C12H22O11)

Please comment below, if from that article is wrong. Thank's

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