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Some basic facts about electrons - Electron movement in an atom .. Electronics

Some basic facts about electrons

Movement of electrons in an atom

A simple or complex picture of an atom can be drawn as needed.

A hydrogen atom can be shown to consist of a central nucleus or proton surrounded by a single electron (1). The proton usually carries a positive charge, and has a mass equal to 1840 times the mass of the electron, which in turn carries a negative charge.

The electron orbits the nucleus millions of times in less than a millionth of a second. We usually need hundreds of millions of nuclei, one next to the other, to fill just one inch. The positive charges are balanced with the negative charges in the atom (protons and electrons) so that the atom appears without an excess of charge, i.e. without an increase of either charge over the other.

The helium atom contains two electrons and two protons, while the atoms of heavier elements contain a larger number of electrons (2). For example, the uranium atom contains 94 electrons, and does not carry any excess charge due to the balance between the negative electrons on the one hand and the positive charge of the nucleus on the other hand.

In addition to the protons and electrons, the nucleus contains many other particles, such as the neutron, which does not carry any charge and which some atoms contain.

Other passing particles sometimes appear, change their state or disappear apparently in their energy. It is possible for an electron in a hydrogen atom to absorb a photon or a light particle, and derive energy from it that raises it to an orbit with a higher energy than its original orbit. It is also possible for electrons to collide with each other, lose part of their energy and descend to orbits of lower energy, and as a result, photons are emitted from them.

Excess charge

In normal conditions, the negative charges carried by electrons are balanced by the positive charges carried by the nucleus. Therefore, the atom does not carry any excess charge. However, sometimes, the atom may gain an extra electron, and then it has an excess negative charge. However, if the atom loses an electron, the number of positive protons in the nucleus exceeds the number of negative electrons, and in this case the atom carries an excess positive charge. In the case of semiconductors, we can talk about positive "holes" or charge-carrying holes. These holes can be imagined as spaces that can be filled with negatively charged electrons to power them. Bodies that contain excess electrons usually carry a negative charge. Bodies that lose a number of their electrons usually carry.

1 - A simplified picture of a hydrogen atom.

2 - Heavy atoms contain a greater number of electrons.

Positive charge (3). Therefore, there is always a difference in potential between charged bodies and neutral bodies unless there is a way to allow the negative bodies to lose their excess electrons or the atoms of the positive bodies to gain the electrons they lack.

If electrons are allowed to move freely in the space between positive and negative charges, they move in this conductive path to occupy a place around the nuclei of positively charged bodies that suffer from a deficiency in the number of their electrons. This movement is nothing but an electric current capable of passing through (4) any conductor such as a metal wire.

Electric current

To ensure the continuity of the electric current, it is necessary to generate or produce a surplus of negative charges continuously to work to replace new electrons instead of those that left their place in the wire. In any device, the current can pass from the negative terminal of the battery to the lamp or to any other device, and return again to the positive terminal of the battery through another conductor and the conductive connections, along with the rest of the devices, form what is called an electric circuit.

The number of electrons can be increased at one end of the circuit and kept in this state in a chemical way,

3 - The potential difference between two different charges.

4 - The flow of negative electrons under the influence of the positive charge.

Using a battery, for example. This method is easy and widely used in portable devices. These electrons can also be produced and increased by electromagnetic methods using a generator, or by photovoltaic cells that have the ability to produce electric current under the influence of photons or light particles, or by using thermal couplers or connections made of different metals to produce electric current when the temperature of these couplers or connections is raised.