The name "atom" is translated from Greek as "indivisible". Everything around us - solids, liquids and air - is built from billions of these particles.
The appearance of the version about the atom
Atoms first became known in the 5th century BC, 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 the only way scientists could 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 19th century. they began to be analyzed as the smallest constituents of chemical elements, having the specific properties of atoms - the ability to enter into compounds with others in a strictly prescribed amount. At the beginning of the 20th century, it was believed that atoms were the smallest particles of matter, until it was proved that they were made up of even smaller units.
What is a chemical element made of?
Atom of a chemical element is a microscopic building block of matter. The molecular weight of the atom has become the defining feature of this microparticle. Only the discovery of Mendeleev's periodic law substantiated that their types are various forms of a single matter. They are so small that they cannot be seen using ordinary microscopes, only the most powerful electronic devices. In comparison, a hair on a human hand is a million times wider.
The electronic structure of an atom has a nucleus, consisting of neutrons and protons, as well as electrons, which make revolutions 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 forces in the universe. Neutrons are particles with a neutral charge, protons are endowed with a positive charge, and electrons with a negative one. The latter are attracted to positively charged protons, so they tend to stay in orbit.
Atom structure
In the central part there is a nucleus that fills the minimum part of the entire atom. But studies show that almost the entire mass (99.9%) is located in it. Every atom contains protons, neutrons, electrons. The number of rotating electrons in it is equal to the positive central charge. Particles with the same nuclear charge Z, but different atomic mass A and the number of neutrons in the nucleus N are called isotopes, and with the same A and different Z and N are called isobars. Electron is the smallest particle of matter with a negativeelectric charge e=1.6 10-19 coulomb. The charge of an ion determines the number of electrons lost or gained. The process of metamorphosis of a neutral atom into a charged ion is called ionization.
New version of the atom model
Physicists have discovered many other elementary particles to date. The electronic structure of the atom has a new version.
It is believed that protons and neutrons, no matter how small they are, consist of the smallest particles called quarks. They constitute a new model for the construction of the atom. As scientists used to collect evidence for the existence of the previous model, today they are trying to prove the existence of quarks.
RTM is the device of the future
Modern scientists can see atomic particles of a substance on a computer monitor, as well as move them over the surface using a special tool called a scanning tunneling microscope (RTM).
This is a computerized tool with a tip that moves very gently near the surface of the material. As the tip moves, electrons move through the gap between the tip and the surface. Although the material looks perfectly smooth, it is actually uneven at the atomic level. The computer makes a map of the surface of matter, creating an image of its particles, and thus scientists can see the properties of the atom.
Radioactive particles
Negatively charged ions circle around the nucleus at a sufficiently large distance. The structure of an atom is such that it is wholeis truly neutral and has no electrical charge because all of its particles (protons, neutrons, electrons) are in balance.
A radioactive atom is an element that can be easily split. Its center consists of many protons and neutrons. The only exception is the diagram of the hydrogen atom, which has one single proton. The nucleus is surrounded by a cloud of electrons, it is their attraction that makes them rotate around the center. Protons with the same charge repel each other.
This is not a problem for most small particles that have several of them. But some of them are unstable, especially large ones like uranium, which has 92 protons. Sometimes his center can 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 the protons, the remaining protons form a new daughter. It can be stable depending on the number of protons in the new nucleus, or it can divide further. This process continues until a stable child core remains.
Properties of atoms
Physical and chemical properties of an atom naturally change from one element to another. They are defined by the following main parameters.
Atomic mass. Since the main place of the 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 Mendeleev system, chemicalbonds, number of neighboring atoms and quantum mechanical action. The radius of the core is one hundred thousand times smaller than the radius of the element itself. The structure of an atom can lose electrons and become a positive ion, or add electrons and become a negative ion.
In the periodic system of Mendeleev, any chemical element takes its assigned place. In the table, the size of an atom increases as you move from top to bottom and decreases as you move from left to right. From this, the smallest element is helium and the largest is cesium.
Valency. The outer electron shell of an atom is called the valence shell, and the electrons in it have received the corresponding name - valence electrons. Their number determines how an atom is connected to the others by means of a chemical bond. By the method of creating the last microparticle, they try to fill their outer valence shells.
Gravity, attraction is the force that keeps the planets in orbit, because of it objects released from the hands fall to the floor. A person notices gravity more, but the electromagnetic action is many times more powerful. The force that attracts (or repels) charged particles in an atom is 1,000,000,000,000,000,000,000,000,000,000,000 times more powerful than gravity in it. But there is an even stronger force at the center of the nucleus that can hold protons and neutrons together.
Reactions in nuclei create energy like in nuclear reactors where atoms are split. The heavier the element, the more particles its atoms are built from. If we add up the total number of protons and neutrons in an element, we find out itmass. For example, Uranium, the heaviest element found in nature, has an atomic mass of 235 or 238.
Dividing an atom into levels
The energy levels of an atom are the size of the space around the nucleus, where the electron is in motion. There are 7 orbitals in total, 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 has. The period number indicates the number of atomic orbitals around its nucleus. For example, Potassium is an element of the 4th period, which means that it has 4 energy levels of the atom. The number of a chemical element corresponds to its charge and the number of electrons around the nucleus.
Atom is a source of energy
Probably the most famous scientific formula was discovered by the German physicist Einstein. She claims that mass is nothing but a form of energy. Based on this theory, it is possible to turn matter into energy and calculate by the formula how much of it can be obtained. The first practical result of this transformation was atomic bombs, which were first tested in the Los Alamos desert (USA), and then exploded over Japanese cities. And although only a seventh of the explosive turned into energy, the destructive power of the atomic bomb was terrible.
In order for the core to release its energy, it must collapse. To split it, it is necessary to act with a neutron from outside. Then the nucleus breaks up into two other, lighter ones, 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, resulting in a huge amount of energy.
Pros and cons of using nuclear reaction in our time
Destructive force, which is released during the transformation of matter, humanity is trying to tame at nuclear power plants. Here, the nuclear reaction does not take place in the form of an explosion, but as a gradual release of heat.
Production of atomic energy has its pros and cons. According to scientists, in order to maintain our civilization at a high level, it is necessary to use this huge source of energy. But it should also be taken into account that even the most modern developments cannot guarantee the complete safety of nuclear power plants. In addition, radioactive waste produced during energy production, if stored improperly, can affect our descendants for tens of thousands of years.
After the accident at the Chernobyl nuclear power plant, more and more people consider the production of nuclear energy to be very dangerous for humanity. The only safe power plant of this kind is the Sun with its huge nuclear energy. Scientists are developing all kinds of models of solar cells, and perhaps in the near future, humanity will be able to provide itself with safe atomic energy.
