Everything around us on the planet consists of small particles that are elusive to vision. Electrons are one of them. Their discovery occurred relatively recently. And it opened up new ideas about the structure of the atom, the mechanisms of transmission of electricity and the structure of the world as a whole.
How to divide the indivisible
In the modern sense, electrons are elementary particles. They are holistic and do not split into smaller structures. But such a view did not always exist. Until 1897, they had no idea about electrons.
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 has been preserved for centuries.
The idea of ​​an atom changed only at the end of the 19th century. After the research of J. Thomson, E. Rutherford, H. Lorenz, P. Zeeman, atomic nuclei and electrons were recognized as the smallest indivisible particles. Over time, protons, neutrons were discovered, and even later - neutrinos, kaons, pi-mesons, etc.
Now science knows a huge number of elementary particles, electrons invariably occupy their place among them.
Discovery of a new particle
By the time electrons in the atom were discovered , scientists had long been aware of the existence of electricity and magnetism. But the true nature and full properties of these phenomena are still a mystery, occupying the minds of many physicists.
Already at the beginning of the XIX 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 report, where he presented to the scientific community the birth of a new particle in the composition of the atom, which he called the corpuscle. Ernest Rutherford later, using experiments with foil, confirmed the conclusions of his teacher, and the corpuscles were given a different name - “electrons”.
This discovery pushed 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 still remains largely contradictory and incomplete. For example, in modern concepts, they live forever, since they never decay, unlike neutrons and protons (the theoretical decay of the latter exceeds the age of the Universe).
Electrons are stable and have a constant negative charge e = 1.6 x 10 -19 C. They belong to the family of fermions and the group of leptons. Particles are involved in weak electromagnetic and gravitational interactions. They are part of 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 the proton. They have half-integer and spin, and magnetic moment. The electron is indicated by the letter "e - ". Also, but with a plus sign, its antagonist is indicated - the positron antiparticle.
The state of electrons in an atom
When it turned out that the atom consists of smaller structures, it was necessary to understand how exactly they are located in it. Therefore, at the end of the 19th century, the first atomic models appeared. According to 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 the atom, where the electrons are represented in the form of a cloud of a certain density with a charge.
Accurately determine the location and trajectory of the electrons around the nucleus is almost impossible. In this regard, the special concept of “orbital” or “electronic cloud” is introduced, which is the space of the most probable location of these particles.
Energy levels
There are exactly as many electrons in a cloud around an atom as there are protons in its core. All of them are at different distances. Closest to the core are the electrons with the least amount of energy. The more energy is in the particles, the farther they can be.
But they are not located randomly, but occupy specific levels that contain 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.
To describe the characteristics and arrangement of electrons at energy levels, four quantum numbers are used :
- n is the main number that determines the energy reserve of the electron (corresponds to the period number of the chemical element);
- l is the orbital number that describes the shape of the electron cloud (s is spherical, p is the figure of eight, d is the shape of clover or double eight, f is the complex geometric shape);
- m is the magnetic number that determines the orientation of the cloud in a magnetic field;
- ms is the spin number characterizing the rotation of electrons around its axis.
Conclusion
So, electrons are stable negatively charged particles. They are elementary and cannot decay into other elements. They are referred to as fundamental particles, that is, those that are included in 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 are involved in electromagnetic and gravitational interactions. Their directional movement creates an electric current and a magnetic field.