Everything around us on the planet consists of small, elusive particles. Electrons are one of them. Their discovery happened relatively recently. And it opened up new ideas about the structure of the atom, the mechanisms for transmitting electricity and the structure of the world as a whole.
How the indivisible was divided
In the modern sense, electrons are elementary particles. They are integral and do not break into smaller structures. But such an idea did not always exist. Electrons were unknown until 1897.
Even the thinkers of Ancient Greece guessed that every thing in the world, like a building, consists of many microscopic "bricks". The atom was then considered the smallest unit of matter, and this belief persisted for centuries.
The notion of the atom changed only at the end of the 19th century. After the studies of J. Thomson, E. Rutherford, H. Lorentz, P. Zeeman, atomic nuclei and electrons were recognized as the smallest indivisible particles. Over time, protons, neutrons, and even later - neutrinos, kaons, pi-mesons, etc. were discovered.
Now science knows a huge number of elementary particles, among which electrons invariably occupy their place.
Discovery of a new particle
By the time electrons were discovered in the atom, scientists had long known about the existence of electricity and magnetism. But the true nature and full properties of these phenomena still remain a mystery, occupying the minds of many physicists.
Already at the beginning of the 19th century, it was known that the propagation of electromagnetic radiation occurs at the speed of light. However, the Englishman Joseph Thomson, conducting experiments with cathode rays, concluded that they consist of many small grains, the mass of which is less than atomic.
In April 1897, Thomson made a presentation, where he presented to the scientific community the birth of a new particle in the atom, which he called a corpuscle. Later, Ernest Rutherford, with the help of experiments with foil, confirmed the conclusions of his teacher, and corpuscles were given a different name - "electrons".
This discovery spurred the development of not only physical but also chemical science. It allowed significant progress in the study of electricity and magnetism, the properties of substances, and also gave rise to nuclear physics.
What is an electron?
Electrons are the lightest particles that have an electric charge. Our knowledge of them is still largely contradictory and incomplete. For example, in modern concepts, they live forever, since they never decay, unlike neutrons and protons (the theoretical decay age of the latter exceeds the age of the Universe).
Electrons are stable and have a permanent negative charge e=1.6 x 10-19Cl. They belong to the fermion family and the lepton group. Particles participate in weak electromagnetic and gravitational interaction. They are found in atoms. Particles that have lost contact with atoms are free electrons.
The mass of electrons is 9.1 x 10-31 kg and is 1836 times less than the mass of a proton. They have half-integer spin and magnetic moment. An electron is denoted by the letter "e-". In the same way, but with a plus sign, its antagonist is indicated - the positron antiparticle.
The state of electrons in an atom
When it became clear that the atom consists of smaller structures, it was necessary to understand exactly how they are arranged in it. Therefore, at the end of the 19th century, the first models of the atom appeared. According to the Planetary models, protons (positively charged) and neutrons (neutral) made up the atomic nucleus. And around it, electrons moved in elliptical orbits.
These ideas change with the advent of quantum physics at the beginning of the 20th century. Louis de Broglie puts forward the theory that the electron manifests itself not only as a particle, but also as a wave. Erwin Schrödinger creates a wave model of an atom, where electrons are represented as a cloud of a certain density with a charge.
It is almost impossible to accurately determine the location and trajectory of electrons around the nucleus. In this regard, a special concept of "orbital" or "electron cloud" is introduced, which is the space of the most probable locationnamed particles.
Energy Levels
There are exactly as many electrons in the cloud around an atom as there are protons in its nucleus. All of them are at different distances. Closest to the nucleus are the electrons with the least amount of energy. The more energy the particles have, the farther they can go.
But they are not arranged randomly, but occupy specific levels that can accommodate only a certain number of particles. Each level has its own amount of energy and is divided into sublevels, and those, in turn, into orbitals.
Four quantum numbers are used to describe the characteristics and arrangement of electrons on energy levels:
- n - the main number that determines the energy of the electron (corresponds to the number of the period of the chemical element);
- l - orbital number that describes the shape of the electron cloud (s - spherical, p - eight shape, d - clover or double eight shape, f - complex geometric shape);
- m is a magnetic number that determines the orientation of the cloud in a magnetic field;
- ms is a spin number that characterizes the rotation of electrons around its axis.
Conclusion
So, electrons are stable negatively charged particles. They are elemental and cannot decay into other elements. They are classified as fundamental particles, that is, those that are part of the structure of matter.
Electrons move around atomic nuclei and make up their electron shell. They affect the chemical, optical,mechanical and magnetic properties of various substances. These particles participate in electromagnetic and gravitational interaction. Their directional movement creates an electric current and a magnetic field.
