Atom is a unique particle of the universe. This article will try to convey to the reader information about this element of matter. Here we will consider such questions: what is the diameter of an atom and its size, what are its qualitative parameters, what is its role in the Universe.
Acquaintance with the atom
Atom is a compound particle of substances that has microscopic size and mass. This is the smallest part of elements of a chemical nature with incredibly small size and mass.
Atoms are built from two main structural elements, namely from electrons and the atomic nucleus, which, in turn, is formed by protons and neutrons. The number of protons may differ from the number of neutrons. Both in chemistry and in physics, atoms in which the magnitude of protons is comparable with the number of electrons are called electrically neutral. If the number of electrons is higher or lower than the number of protons, then the atom, acquiring a positive or negative charge, becomes an ion.
Atoms and molecules in physics have long been considered the smallest "bricks" from which the Universe is built, and even after the discovery of even smaller components, they remain among the most important discoveries in the history of mankind. It is the atoms bonded via interatomic bonds that form the molecules. The bulk of the atom is concentrated in the nucleus, namely, in the weight of its protons, which make up about 99.9% of the total value.
Historical data
Thanks to the achievements of science in the field of physics and chemistry, many discoveries have been made regarding the nature of the atom, its structure and capabilities. Numerous experiments and calculations were carried out, during which a person was able to answer such questions: what is the diameter of the atom, its size, and much more.
For the first time, the concept of an atom was discovered and formulated by philosophers of ancient Greece and Rome. In the XVII – XVIII centuries, chemists were able to experimentally prove the idea of an atom as the smallest particle of matter. They showed that many substances can be broken down repeatedly using chemical methods. However, later subatomic particles discovered by physicists showed that even an atom can be separated, and it is built from subatomic components.
The International Congress of Scientists in Chemistry in Karlsruhe, located in Germany, in 1860 decided on the concept of atoms and molecules, where the atom is considered as the smallest part of chemical elements. Therefore, it is also part of substances of a simple and complex type.
The diameter of the hydrogen atom was studied one of the very first. However, his calculations were made many times and the last of them, published in 2010, showed that it is 4% less than previously expected (10 -8 ). The indicator of the total value of the size of the atomic nucleus corresponds to the number 10 -13 -10 -12 , and the order of magnitude of the entire diameter is 10 -8 . This caused a lot of contradictions and problems, since hydrogen itself rightfully belongs to the main components of the entire observable Universe, and such a mismatch forces to make many recalculations with respect to fundamental statements.
Atom and its model
At present, five basic atomic models are known that differ from each other, first of all, in the time frame of ideas about its structure. Let's consider the models directly:
- The pieces that make up matter. Democritus believed that any property of substances should be determined by its forms, mass and other series of practical characteristics. For example, a fire can burn because its atoms are sharp. According to Democritus, even the soul is formed by atoms.
- Thomson's atomic model, created in 1904, by J.J. Thomson himself. He suggested that the atom can be taken as a positively charged body, enclosed inside electrons.
- The early planetary atomic model of Nagaoka, created in 1904, believed that the structure of the atom is similar to the Saturn system. The nucleus is small in size and has a positive charge indicator surrounded by electrons that move along the rings.
- Atomic planetary model discovered by Bohr and Rutherford. In 1911, E. Rutherford, after conducting a series of experiments, began to believe that the atom is similar to the planetary system, where the electrons have orbits along which they move around the nucleus. However, this assumption went against the data of classical electrodynamics. To prove the validity of this theory, Niels Bohr introduced the concept of postulates that assert and show that the electron does not need to expend energy, since it is in a specific, special energy state. The study of the atom subsequently led to the emergence of quantum mechanics, which was able to explain the many contradictions that could be observed.
- The quantum-mechanical atomic model claims that the central basis of the particle in question consists of a nucleus formed from protons, as well as neutrons and electrons moving around it.
Structural features
The size of an atom previously determined that it was an indivisible particle. However, many experiments and experiments have shown us that it is built from subatomic particles. Any atom consists of electrons, protons and neutrons, with the exception of hydrogen - 1, which does not include the latter.
The standard model shows that protons and neutrons are formed through interactions between quarks. They belong to fermions, along with leptons. Currently, there are 6 types of quarks. Protons owe their formation to two u-quarks and one d-quark, and a neutron - to one u-quark and two d-quarks. Strong-type nuclear interactions that bind quarks are transmitted via gluons.
The motion of electrons in atomic space is predetermined by their “desire” to be closer to the nucleus, in other words, attracted, as well as by the Coulomb forces of interaction between them. The same types of forces hold each electron in a potential barrier surrounding the nucleus. The orbit of the motion of electrons determines the diameter of the atom, equal to a straight line passing from one point in a circle to another, as well as through the center.
The atom has its spin, which is represented by its own momentum and lies outside the understanding of the general nature of matter. It is described using quantum mechanics.
Dimensions and Weight
Each nucleus of an atom with the same number of protons refers to a common chemical element. The isotopes include representatives of atoms of one element, but having a difference in neutron quantity.
Since the structure of the atom in physics indicates that their main mass is made up of protons and neutrons, the total amount of these particles has a mass number. The expression of atomic mass in a state of calm occurs through the use of atomic mass units (i.e., m.), Which are also called daltons (Yes).
The size of an atom has no distinct boundaries. Therefore, it is determined by measuring the distance between the nuclei of the same type of atoms chemically bonded to each other. Another method of measurement is possible when calculating the duration of the path from the nucleus to the further of the available stable electron type orbits. The periodic system of elements of D. I. Mendeleev has atoms in size, from smaller to large, in the direction of the column from top to bottom, movement in the direction from left to right is also based on a decrease in their size.
Decay time
All chem. elements have isotopes from one and above. They contain an unstable core, subject to radioactive decay, resulting in the emission of particles or electromagnetic radiation. Radioactive is the isotope in which the value of the radius of the strong interaction goes beyond the far points of the diameter. If we consider the example of an aurum, then the Au atom is the isotope, beyond the limits of the diameter of which in all directions the emitted particles “fly out”. Initially, the diameter of a gold atom corresponds to a value of two radii, each of which is equal to 144 pc, and particles that go beyond this distance from the nucleus will be considered isotopes. There are three types of decay: alpha, beta and gamma radiation.
The concept of valency and the presence of energy levels
We have already got acquainted with the answers to such questions: what is the diameter of an atom, its size, got acquainted with the concept of atom decay, etc. However, in addition to this, there are also such characteristics of atoms as the magnitude of energy levels and valency.
Electrons moving around an atomic nucleus have potential energy and are in a bound state, located at an excited level. According to the quantum model, an electron occupies only a discrete number of energy levels.
Valence is the general ability of atoms in which there is free space on the electron shell to establish bonds of the chemical type with other atomic units. Through the establishment of chemical bonds, atoms try to fill their layer of the outer valence shell.
Ionization
As a result of the effect of a high value of tension on the atom, it can undergo irreversible deformation, which is accompanied by electronic separation.
This leads to ionization of the atoms, during which they give away the electron (s) and undergo a transformation from a stable state into ions with a positive charge, otherwise referred to as cations. This process requires a certain energy, which is called the ionization potential.
To summarize
Studying questions about the structure, interaction features, qualitative parameters, about the diameter of an atom and its dimensions, all this allowed the human mind to perform incredible work that helps to better understand and understand the structure of all matter around us. These same questions made it possible for a person to open up concepts about the electronegativity of an atom, its disperse attraction, valence potentials, determine the duration of radioactive decay, and much more.