Atoms and Elements

WHAT IS ATOM?

Atoms  are the building blocks of all matter that exists. They are so small that we can not even see with our naked eyes. Atoms usually in the range of Angstrom.

After much experimentation, the atomic structure described in the 19th century. Atoms consist of a nucleus, which has a proton and a neutron. In addition to neutrons and positrons there are other small sub-atomic particles in the nucleus. And there are electrons circling the nucleus in the orbital.

Most of the atom is empty space. A force that pulls the positively charged nucleus (positive charge because protons) and electrons are negatively charged atoms maintain the shape. Both protons and neutrons are nucleons. They were together in atomic nuclei bound by the nuclear force.

THEORIES ABOUT ATOM

1. Dalton's Theory

   John Dalton, a British chemist and physicist, developed a theory that matter is simply composed of atoms of different weights and is combined in ratios by weight. Also proposed that these atoms are spherical, and are in motion. 

    

   2. J.J Thomson's Theory

   

   Based on the discovery of a cathode tube better by William Crookers, then J.J. Thomson further research cathode rays and can be ascertained that the cathode rays are particles.
   
   From these findings, Thomson rectify the shortcomings of dalton atomic theory and atomic theory put forward known as Thomson's Atomic Theory. Which states that:
   
   "Atom is a solid ball which is positively charged and dispersed inside negative charge of electrons"

   3. Rutherford's Theory

   

   Rutherford along with two of his disciples (Hans Geigerdan Erners Masreden) conducted an experiment known as alpha ray scattering on thin plates of gold.
   
   From their observations, it was found the fact that when alpha particles fired at a very thin gold plate, then most of the alpha particles passed.
   
   Based on the phenomena that occur, Atom is not a solid ball, because nearly all of the alpha particles passed. If the gold plate is considered as a single layer of atoms of gold, the gold atoms contained in very small particles are positively charged. 

   4. Bohr's Theory

   

   In 1913, the Danish physicist Neils Bohr called Rutherford atom fix failures through experiments on the spectrum of the hydrogen atom. His experiment managed to give a picture of the electrons to occupy the area around the atomic nucleus. Explanation of the hydrogen atom Bohr involves a combination of the classical theory of Rutherford and Planck's quantum theory.
   
   According to the Bohr model of the atom, the electrons around the nucleus at a specific trajectories called electron shells or energy levels. The lowest energy level is located at the electron shells in, getting out the greater number of his skin and the higher energy level. 

   5. Schrodinger's  Theory or Quantum's Mechanical

   

   The theory of quantum mechanical known as the uncertainty principle, which is "not possible to determine the position and momentum of an object carefully at the same time, which can be determined is the probability of finding the electron at a certain distance from the nucleus."
   
   The area around the core space with the probability of getting called orbital electrons. The shape and energy orbital Schrodinger.Erwin Erwin Schrodinger formulated by solving an equation to get the wave function to describe the limits of the possible discovery of electrons in three dimensions. 

    

    ATOM'S COMPONENTS

   ElectronElectrons are subatomic particles (smaller than an atom) particle that carries a negative electric unit. All matter is composed of atoms which, in turn, contains three very small particles: protons, neutrons, and electrons.Of the three, only the electrons are considered elementary particles, ie, incapable of being broken down into simpler particles.The presence or absence of an excess of electrons is responsible for all electrical phenomena. Suppose the metal wire is connected to the two ends of the battery. Electric pressure of the electrons in the electron battery powers the metal atoms flowing. The flow of electrons is an electrical current.
   ProtonProtons are subatomic particles inside the atomic nucleus and have a positive charge. Proton generally denoted as p. When electrons are found, scientists do not know about particles called protons. Goldstein found a positively charged particles generated from gas. This is known as the anode beam. Unlike electrons, it has the opposite charge to mass ratio depending on the gas used. After numerous experiments by many scientists, finally Rutherford discovered protons in 1917.The number of protons is important to show the atomic number, due to the element, atomic number is equal to the number of protons in the nucleus. For example, sodium atomic number is 11; Therefore, sodium has eleven electrons in the core. Protons have a charge of +1, and its mass is 1.6726 × 10-27 kg. Proton said to be composed of three quarks, two up quarks and one down quark. The simplest elements, hydrogen has only one proton. When a hydrogen atom loses electrons, forming H + ions, which has a proton.Therefore, in chemistry, the term "proton" is used to refer to H + ions. H + is important in acid-base reaction and, this is a highly reactive species. There is more than one proton in all other elements except hydrogen. Usually a neutral atom, the number of negatively charged electrons and positively charged protons same amount.
   NeutronNeutron is another sub atomic particles found in the nuclei of atoms. This is indicated by the symbol n. Neutrons have no electric charge. Had a bit of the same mass as compared to protons, but the mass of the neutron is slightly larger than a proton. Therefore, neutrons are considered when determining the atomic mass number. The same type of atom may be different because of the number of these neutrons, and these are known as isotopes.Rutherford put forward the possibility of having particles such as neutrons in the nucleus. Then after a series of experiments, Chadwick prove this and find a neutron. Neutron consists of three quarks, two down quarks and one quark and upwards. Free neutrons are unstable and have very short half-life. Neutrons are important in nuclear reactions.