The name "atom" from the Greek means "indivisible." Everything around us — solids, liquids, and air — is made up of billions of these particles.
For the first time about atoms became known in the V century beforeAD, when the Greek philosopher Democritus suggested that matter consists of moving tiny particles. But then it was not possible to check the version of their existence. And although no one could see these particles, the idea was discussed, because only in this way could scientists explain the processes occurring in the real world. Therefore, they believed in the existence of microparticles long before they could prove this fact.
Only in the XIX century.they began to be analyzed as the smallest components of chemical elements that have specific properties of atoms — the ability to join compounds with others in a strictly designated quantity. At the beginning of the 20th century, it was believed that atoms were minimal particles of matter, until it was proved that they consist of even smaller units.
Атом химического элемента – микроскопический building blocks of matter. The molecular mass of the atom has become the determining feature of this microparticle. Only the discovery of the periodic law of Mendeleev proved that their types are diverse forms of a single matter. They are so small that they can not be seen using conventional microscopes, only the most powerful electronic devices. For comparison, the hair on a person’s hand is a million times wider.
Электронная структура атома имеет ядро, состоящее from neutrons and protons, as well as electrons that rotate around the center in constant orbits, like planets around their stars. All of them are held together by electromagnetic force, one of the four main ones in the universe. Neutrons are particles with a neutral charge, protons are endowed with a positive, and electrons are negative. The latter are attracted to positively charged protons, so they tend to remain in orbit.
In the central part there is a core that fillsminimal part of the whole atom. But studies show that almost the entire mass (99.9%) is located exactly in it. Each atom contains protons, neutrons, electrons. The number of rotating electrons in it is equal to a positive central charge. Particles with the same nuclear charge Z, but different atomic masses A and the number of neutrons in the nucleus N are called isotopes, and with the same A and different Z and N - isobars. The electron is the minimum particle of a substance with a negative electric charge e = 1.6 · 10-19 pendants. The ion charge determines the number of electrons lost or added. The process of metamorphosis of a neutral atom into a charged ion is called ionization.
Physicists have discovered today many other elementary particles. The electronic structure of the atom has a new version.
Считается, что протоны и нейтроны, какими бы they were not small, they consist of the smallest particles, which are called quarks. They constitute a new model of building an atom. As before, scientists collected evidence for the existence of the previous model, and today they are trying to prove the existence of quarks.
Modern scientists can see on the monitorcomputer atomic particles of matter, as well as moving them along the surface, using a special tool, which is called a raster tunnel microscope (RTM).
it computerized инструмент с наконечником, который очень moves gently near the surface of the material. When the tip moves, the electrons move through the gap between the tip and the surface. Although the material looks completely smooth, in fact it is uneven at the atomic level. A computer makes a map of the surface of a substance, creating an image of its particles, and scientists can thus see the properties of an atom.
Negatively charged ions swirl around the nucleus.at a sufficiently large distance. The structure of the atom is such that the whole is truly neutral and has no electric charge, because all its particles (protons, neutrons, electrons) are in balance.
A radioactive atom is an element that caneasy to split. Its center consists of many protons and neutrons. The only exception is the scheme of the hydrogen atom, which has a single proton. The nucleus is surrounded by a cloud of electrons, it is their attraction that makes it rotate around the center. Protons with the same charge repel each other.
Это не проблема для большинства небольших частиц, who have several. But some of them are unstable, especially for large ones, such as uranium, which has 92 protons. Sometimes its center does not withstand such a load. They are called radioactive because they emit several particles from their core. After the unstable nucleus has got rid of protons, the remaining ones form a new daughter. It may be stable depending on the number of protons in the new nucleus, and may be further divided. This process lasts until a stable daughter nucleus remains.
The physicochemical properties of an atom naturally change from one element to another. They are determined by the following main parameters.
Atomic mass. Since the main place of microparticles is occupied by protons and neutrons, their sum determines the number, which is expressed in atomic mass units (amu) Formula: A = Z + N.
Atomic radius.The radius depends on the location of the element in the periodic system, chemical bonding, the number of atoms-neighbors and quantum-mechanical action. The core radius is a hundred thousand times smaller than the radius of the element itself. The structure of the atom can lose electrons and turn into a positive ion or add electrons, and become a negative ion.
In the periodic system of anychemical element takes its established place. In the table, the size of the atom increases when moving from top to bottom and decreases when moving from left to right. Following from this, the smallest element is helium, and the largest is cesium.
Valence.The outer electron shell of an atom is called the valence, and the electrons in it are given the corresponding name - the valence electrons. Their number establishes how the atom combines with the rest through chemical bonding. By creating the latter, microparticles try to fill their outer valence shells.
Gravity, attraction is the force that holdsthe planets are in orbit, because of her objects dropped from her hands fall to the floor. A person notices gravity more, but electromagnetic action is many times more powerful. The force that attracts (or repels) charged particles in an atom is 1,000,000,000,000,000,000,000,000,000 times more powerful than gravity in it. But in the center of the nucleus there is an even more powerful force capable of holding protons and neutrons together.
Reactions in nuclei create energy as in nuclearreactors where atoms are split. The heavier the element, the larger the number of particles built by its atoms. If we add up the total number of protons and neutrons in an element, we will know its mass. For example, Uranus, the heaviest element in nature, has an atomic mass of 235 or 238.
The energy levels of the atom is the magnitudespaces around the nucleus where the electron is in motion. In total there are 7 orbitals corresponding to the number of periods in the periodic table. The more distant the location of the electron from the nucleus, the more significant reserve of energy it owns. The period number indicates the number of atomic orbitals around its core. For example, potassium is an element of 4 periods, which means that it has 4 energy levels of the atom. The number of the chemical element corresponds to its charge and the number of electrons around the nucleus.
Probably the most famous scientific formula.opened by the German physicist Einstein. She argues that mass is nothing but a form of energy. Based on this theory, one can turn matter into energy and calculate it using the formula for how much it can be obtained. The first practical result of this transformation was the atomic bombs, which were first tested in the desert of Los Alamos (USA), and then exploded over the Japanese cities. And although only the seventh part of the explosive was turned into energy, the destructive force of the atomic bomb was terrible.
In order for the core to release its energy, itshould collapse. To split it, it is necessary to act outside the neutron. Then the nucleus breaks up into two others, lighter, while providing a huge release of energy. Decay leads to the release of other neutrons, and they continue to split other nuclei. The process turns into a chain reaction, as a result creating a huge amount of energy.
Mankind is trying to tame the destroying force, which is released during the transformation of matter, at nuclear power plants. Here the nuclear reaction occurs not in the form of an explosion, but as a gradual release of heat.
The production of atomic energy has its advantages andminuses. According to scientists, to maintain our civilization at a high level, it is necessary to use this huge source of energy. But it should be borne in mind that even the most modern developments cannot guarantee the complete safety of nuclear power plants. In addition, the radioactive waste produced during energy production during improper storage can affect our descendants for tens of thousands of years.
After the Chernobyl accident, more and morepeople consider the production of atomic energy very dangerous for humanity. The only safe power station of this kind is the Sun with its enormous nuclear power. Scientists are developing various models of solar cells, and perhaps in the near future, mankind will be able to provide themselves with safe atomic energy.
