During school we’ve learned about atoms and their use in life, be it for good or as weapons of mass destruction. And what about the history of the discovery of the atom itself, I am sure there are many people who do not know, here’s his review:
The development of atomic structure was donated by many scientists. Chronology of the atomic structure revealed the discovery of atomic particles and their arrangement in the atom.
Atoms are the building blocks of all matter. An atom consists of three particles – neutrons (no charge), protons (positively charged) and electrons (negatively charged). The number of protons present in the atom is called the atomic number, while the mass of the atom is the number of protons plus the average number of neutrons. Each different elements found in nature differ in the number of third-atomic particles. In general, atomic number used to define an element, for example, an element with atomic number 8 is oxygen and vice versa. An element has a fixed number of protons, but can have varying numbers of neutrons. Atoms with different numbers of neutrons are called as isotopes.
The idea that atoms existed since ancient Greece. This was stated by Democritus (460 BC) as Atoma, a Greek word meaning can not be divided. However, the real praise for the invention of the atom went into John Dalton who proposed the theory of the atom and suggested that all matter consists of solid particles called atoms ball. After the discovery of the atom, many improvements have been made about atoms and atomic structure.
Aristotle around the fourth century BC proposed that the distribution of the material will be continuous which means it can be carried out continuously. There are differences in interpretation between the two groups in the philosophers interpret the word atomos, both agree that atomos means can not be divided again. It’s just that there are significant differences regarding whether or not the concept of atomos used in learning the material.
John Dalton was a British scientist in the Middle Ages used the concept of atoms to explain chemical reactions. According to him, a chemical reaction occurs as a result of the merger and separation atomatom. The number of atoms involved in chemical reactions and compounds is given as well as the separation of the atoms meet certain fixed comparative law.
Law of definite proportions This suggests the existence of other, more fundamental law is the law of conservation of mass; that mass can not be created and can not be destroyed through chemical reactions. Mass-energy equivalence at the time was not yet known. The energy generated in the chemical reactions comes from breaking bonds between atoms. The concept of atom is very widely used to describe chemical reactions without the slightest knowledge of the atom itself.
J.J. Thompson, in the mid 19th century, or more precisely in 1858, JJ Thompson conducted experiments using a discharge tube that produces cathode rays. These rays are electrically charged because it turned out to be deflected by an electric field and a magnetic field. Payload type cathode ray is negative, hereinafter referred to as the electron.
Thompson estimates that the electron is a subatomic elementary particles. Electrons are subatomic particles known to man first. Based on this discovery, Thompson proposed an atomic model to explain the experimental results and the theoretical predictions that emerged at that time with the model name raisin cookie. Atom is seen as a sphere that is neutralized by the positively charged electrons are spread evenly throughout the volume of the ball.
Rutherford along with two of his disciples (Hans Geigerdan Erners Masreden) conducted an experiment known as alpha-ray scattering (λ) on thin plates of gold. Previously it has been found for alpha particles, which particles are positively charged and move straight, great penetrating power that can penetrate thin sheets of paper. The experiment aims to examine the actual opinion of Thomson, namely whether the atom was really a solid ball which is positive when subjected to alpha particles would be reflected or deflected.
In 1912, when Neils Bohr (1885-1962) became student of Rutherford at Manchester University. Bohr knew that this orbital model, although very interesting, is not corrected at all, because it can not explain, for example, why the whole of hydrogen atoms have identical chemical properties.
Based on classical physics, electrons can not be in orbit in different radius, and consequently there is continuity of the electron energy levels. Notwithstanding the foregoing, the hydrogen goes before all the atoms reserve the same energy. Furthermore, even if the electrons of each atom stems from a stable orbit in particular, at the time its orbit will change due to the collisions between atoms.
Thus the discussion about atoms, I hope this article can add your knowledge about atoms and usefulness in life, thank you.