Electrons are particles that are part of the constitution of the atom. This, in turn, has two main regions, the core (central, dense, compact and massive part) and the electrosphere (a peripheral region around the nucleus). Electrons are in the atom's electrosphere, moving around the nucleus in circular orbits called electron shells.
According to the Rutherford-Bohr atomic model, there are at most seven electronic layers, but only a few circular orbits are allowed for the electron because, in each of these orbits, the electron has energy constant.
The word "electron" comes from the Greek elektron, which means amber — a resin excreted by certain types of vegetables to protect against insects and microorganisms. Over time, this resin loses water and hardens, becoming a fossilized resin. Greek philosopher Thales of Mileto (625 a. Ç. - 546 a. C.) observed that, when rubbing amber with fabrics such as silk, wool or suede, it began to attract light objects, becoming “electrified”.
Scorpion in amber, a fossilized resin
Over time, several discoveries about the electrical nature of matter were made, thus showing that matter had negative and positive charges in its constitution. But it was only in 1856 that the explanation for this phenomenon of electricity began to take shape. the english physicist sir Willian Crookes (1832-1919) created what became known as the Crookes ampoule, a sealed glass tube in which they were placed. gases under very low pressures and which had a negative and a positive pole at the ends of the ampoule, the electrodes.
The application of a potential difference between the electrodes generated a light beam, which remained known as cathode ray, as it always went from the negative electrode (cathode) to the positive electrode (anode).
Years later, in 1897, the English scientist Joseph John Thomson (1856-1940) carried out further experiments with this cathode ray tube that culminated in the discovery of electrons. He concluded the following:
* These cathode rays are an integral part of all matter, because even changing the gases, the result for this experiment is repeated. Thus, it is about a subatomic particle;
* These rays have pasta because they are able to move a small helix inside the tube;
* They have a negative charge because, when placing an electric field outside the bulb, the cathode rays undergo a deflection, being attracted to the positive plate.
Thus, the cathode rays were named as electrons and were considered the first subatomic particle discovered.
Joseph John Thomson (1856-1940) – considered the discoverer of the electron
Today we know that electrons are the smallest mass particles that make up the atom. Are necessary 1836 electrons to arrive at the mass of a proton or a neutron, which are the particles that make up the atomic nucleus. Its relative charge is -1 and, in coulomb, it is -1.602. 10-19.
Here are some interesting aspects about electrons that explain several phenomena we know:
* Electrons emit radiation: Do you know when a little salt falls on the stove flame and the color turns a very intense yellow? This is because, as mentioned, the Rutherford-Bohr atomic model says that electrons are in orbits with a certain amount of energy. When one of these electrons receives energy (such as through heat), it jumps from a lower energy orbit to a higher energy orbit, getting into an excited state. However, this state is unstable and the electron quickly loses the energy it gained in the form of visible radiation, which is the color we visualize, and returns to its ground state.
Each atom has electronic layers with certain amounts of energy, so each salt formed by a type of metal emits a different color radiation. Sodium emits a yellow color, barium emits a green color, lithium emits a red color, aluminum emits a white color, and so on. This principle is used for making fireworks. See more about how this happens through the following experiment: Flame test: electronic transition.
Fireworks are colored due to the use of different salts.
* Electric current and electrons:Electric current is nothing more than an orderly flow of electrons. In metal, there are free electrons that, by the action of an electric or magnetic field, are ordered into a flux within the metal's crystal lattice. This point is very important, as we know that, without electricity, our society would not be the same.
* Electrons are transferred between atoms: Atoms bind by transferring or sharing electrons. following the octet theory, for an atom to be stable, it needs to have eight electrons in its valence shell (outer electronic shell), thus acquiring a noble gas configuration. Therefore, the atoms of the elements transfer or share their atoms through, respectively, ionic bonds or covalent bonds, forming such stable compounds that we have around us and within us.
By Jennifer Fogaça
Graduated in Chemistry
