By Pablo Acuña.

Introduction All materials are made of matter. Matter is anything that has mass and volume. The basic buildings of matter are atoms.

For more than 2400 years, philosophers and scientists have tried to determine the composition of matter using a variety of experiments and observations. This is the history of the atom…

The History of the Atom Democritus ( more than 2000 years ago): He is the first in think about the Atom.Democritus ( more than 2000 years ago): He is the first in think about the Atom. John Dalton: In the early 1800, he proposed a theory. by his studies of the gases.John Dalton: In the early 1800, he proposed a theory. by his studies of the gases. J.J Thomson : In 1897, he discovered the electron studding the passage of an electric current through a gas. He created the model of the “pudding”J.J Thomson : In 1897, he discovered the electron studding the passage of an electric current through a gas. He created the model of the “pudding”

Ernest Rutherford: In 1908, he discovered that the atoms have a nucleus and the electrons fly around, he use the experiment of the golden sheet.Ernest Rutherford: In 1908, he discovered that the atoms have a nucleus and the electrons fly around, he use the experiment of the golden sheet. Niels Bhor: In 1913 Bhor proposed an improvement on the Rutherford model, that the electrons move in definite orbits.Niels Bhor: In 1913 Bhor proposed an improvement on the Rutherford model, that the electrons move in definite orbits. The wave model: Bhor model worked well in explaining the structure of simple atoms, today are based on the principals of wave mechanics, this is that the atoms don’t move about the atom in definite path.The wave model: Bhor model worked well in explaining the structure of simple atoms, today are based on the principals of wave mechanics, this is that the atoms don’t move about the atom in definite path.

Democritus. The greek philosopher Democritus in more than 2000 years ago, he and many others philosopher ask this question: could matter be divided into smaller and smaller pieces for ever, or was there a limit to the number of times a piece of matter could be divided?

Democritus concluded that matter could not be divided into smaller and smaller particles for ever. Eventually the smallest possible piece would be obtained.

John Dalton John Dalton. Dalton proposed that: In the early 1800 John Dalton proposed a theory that said that: All elements are composed of atoms. Atoms are indivisible and indestructible particles.All elements are composed of atoms. Atoms are indivisible and indestructible particles. Atoms of the same element are exactly alike.Atoms of the same element are exactly alike. Atoms of diferent elements are differentAtoms of diferent elements are different Compounds are formed by the joining of atoms of two or more elements.Compounds are formed by the joining of atoms of two or more elements.

J.J. Thomson. Thomson proposed that the atom is divided into smaller particles, he discovered the electron, studying the passage of an electric current through a gas.

He proposed a model called “plum pudding" according to Thomson's atomic model, the atom was made of a puddinglike positively charged material throughout which negatively charged electrons were scattered, like plums in a pudding.

Ernest Rutherford He discovered the separation among the nucleus an the electrons, he did and experiment with a positive ray that passed right through a golden sheet without changed is curse, with a exception of some that change his curse, other that return, and another that go vertical back.

This probe that the positives charges that go through the golden sheet didn’t touch the nucleus, some passed nearly the nucleus and changed his curse, some touched directly the nucleus and return This probe that the positives charges that go through the golden sheet didn’t touch the nucleus, some passed nearly the nucleus and changed his curse, some touched directly the nucleus and return.

Niels Bohr He proposed an improvement in the Rutherford's model, the positions of the electrons, in specifics energy levels, According to Bohr’s atomic model, electrons move in definite orbits around the nucleus, much like planets circle the sun, These orbits, or energy levels, are located at certain distances from the nucleus.

The wave model According to the modern atomic model, an atom has a small positively charged nucleus surrounded by a large region in which there are enough electrons to make the atom neutral.

Know the exact location of the electron is impossible, the scientist only can predict where an electron is most likely to be found.