Definition of the atom and its components

 atom definition


The science of chemistry: is the science of chemistry that is concerned with the properties of substances, their composition, structure, the transformations they undergo, and the energy that is released or absorbed during these transformations. Every substance, whether natural or artificially produced, consists of one or more individual types of atoms that have been identified as elements Chemical, and although these atoms, in turn, consist of elementary molecules, they form the basic building blocks of chemical substances so that there is no amount of oxygen, mercury, or gold smaller than the atoms of these substances, so chemistry is not concerned with the subatomic range, but rather with the properties of the atoms, their synthesis and the laws that govern them. And how knowledge of these properties can be exploited to achieve specific purposes, and this article reviews the definition of the atom and its components


History of the atomic theory: Before talking about the definition of the atom and its components, it is necessary to first address the history of atomic theory, as the atomic theory originated as a philosophical concept in ancient India and Greece, and the name "atoms" came originally from the ancient Greek word atomos, which means something indivisible According to the atomic theory, matter consists of separate molecules, however, this theory was one of many explanations that were not based on experimental data, and in the fifth century B.C. the Greek philosopher Democritus proposed that matter consists of indivisible units called atoms, and the Roman poet Lucretius touched upon this idea through his poems, which made it reserved during the Dark Ages for later consideration.


Defining the atom: and its components To define the atom and its components, it is necessary to address the concept of the atom in the science of chemistry, as the atom is the smallest unit in which matter can be divided without the release of electrically charged particles from it and it is also the smallest unit of matter that has the characteristics of a chemical element and as such, the atom is the basic building block of materials.

and the following points summarize the components of the atom:

Protons: Protons are particles with positive charge present inside the nucleus of the atom. They were discovered by the scientist Rutherford in his experiments on cathode ray tubes. The relative mass of protons is 1.673x10-27 kg, and the number of protons in an atom is indicated by the atomic number of this element in addition to the number of Protons that determine the element's chemical behavior.

Electrons: They are negatively charged particles surrounding the nucleus of the atom in paths called orbits, and the relative mass of electrons is about 9.109x10-31 kg, and they were discovered by the scientist Thomson, a British physicist who discovered the electron in 1897, and the shape of the inner orbits of the electrons surrounding the atom is spherical The shape of the outer orbits is much more complex.

Neutrons: Neutrons are uncharged particles present in all nuclei of atoms except for the hydrogen atom and the relative mass of the neutrons is 1.6749x10-27, and the existence of neutrons was discovered by Rutherford in 1920 and their existence was proven by the scientist Chadwick in 1932, where he found the neutrons during the experiments that were made In it the release of atoms to a thin plate of beryllium.

Dalton's atomic theory: After defining the atom and its components, it is necessary to address the most famous theories that explained what the atom is. Until the eighteenth century, there was no experimental evidence for the existence of atoms and it took until the end of the eighteenth century for science to provide tangible evidence for its existence, in 1789 Antoine Lavoisier formulated the law of conservation of mass, which states that the mass of the products of a reaction is equal to the mass of the reactants, then John Dalton built on Lavoisier's law to formulate his law, which states that the atoms of elements combine in fixed numerical proportions to form chemical compounds. Dalton derived his law mainly from Experimental data, and he showed that every chemical element consists of one type of atoms that cannot be divided by any chemical means. This law was presented orally in 1803 while it was published in 1805 and represented the scientific beginning of the atomic theory, and in 1811 the scientist Amedeo Avogadro corrected A problem in Dalton's theory when he showed that equal volumes of gases at equal temperature and pressure contain the same number of molecules, as Avogadro's law allowed the elements to accurately estimate the atomic masses and differentiate Slide between atoms and molecules.

Thomson model and Rutherford model In 1897: Thomson discovered the electron and believed that atoms could be divided, and because the electron carries a negative charge, he proposed a model of the atom that resembles a plum pie where he combined the electrons into a mass with a positive charge to produce an electrically neutral atom, after which Ernest Rutherford, one of the students Thomson refuted this model in 1909 and Rutherford found that the positive charge of the atom and most of its mass was in the center of the nucleus of the atom.

Bohr's model of the atom: Rutherford's model was on the right path, but he could not explain the emission and absorption spectra of the atoms and why the electrons did not collide with the nucleus, and in 1913 Niels Bohr proposed his model which is that electrons orbit around the nucleus in separate energy levels at specific distances from the nucleus, according to For the Bohr model, electrons cannot dock inside the nucleus, but they can make specific jumps between energy levels.


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