If we could divide everything that surrounds us into smaller pieces until we reach the minimum, what would we have?
The answer can be found in atoms and their different parts, but not even science has been able to decipher exactly what happens to such a small level. In any case, the atomic theory has come a long way and this is what we know, so far.

  • Also discover the 20 properties of matter.

1. What is an atom
2. The parts of an atom
3. Properties of an atom

What is an atom
The concept of the atom arose long before the birth of modern quantum physics. In the 5th century BC, the Greek atomists , led by Democritus and Leucippus, proposed something called the “atomic theory of the universe.” For them, everything that surrounded us and was perceptible through the senses was made up of small particles called atoms. For them, atoms had the following properties.

  • They are indivisible, homogeneous and invisible.
  • They only differ in shape and size.
  • The properties of matter change depending on how the atoms are grouped.

Although this philosophical current was not seen with good eyes, the atomists were not too wrong. Science has shown that there is this unit of matter called the atom, but the properties they proposed are not entirely true. As we will see later, atoms can be divided into subatomic particles , so they are not indivisible.
In fact, nuclear fission is the process by which an atomic nucleus splits. The process of fusing two nuclei is called nuclear fusion.
Therefore, we could describe an atom as the smallest unit of matter with its chemical properties. To understand how small an atom is, try to imagine a meter divided into ten billion parts. Impossible, right?
An atom is so small that science (with the means at its disposal today) finds it very difficult to measure things at the atomic level.
The Royal Spanish Academy offers the following definition:
“Particle indivisible by chemical methods, formed by a nucleus surrounded by electrons”

The parts of an atom
Now that we have the concept of an atom clear, we will list the parts and particles that compose it.

Subatomic Particles
Electrons are the lightest particles in an atom and have a negative electric charge. They are elementary particles, which means that they are not made up of smaller particles or have not yet been discovered. Another particle that is part of the atom is the proton, with a positive electric charge. Finally we find the neutrons, which have no electric charge. Both the proton and the neutron are, in turn, made up of quarks, but we will stay to analyze the parts of an atom.
Representation of the structure of an atom. | cubaeduca.cu

1. The nucleus
We could define the nucleus as the “central” zone of the atom. This part is where the protons and neutrons(this tandem is called nucleons) are held together by the nuclear force. The nuclear force is what prevents the protons from shooting out of the nucleus. Earlier we noted that electrons are the lightest particles, so all the mass of the atom comes from the nucleus.
If all the matter that does not surround is made up of particle atoms, what is it that differentiates each element? The answer is relatively simple: the number of protons it contains. Have you ever seen a number next to each element in the periodic table? That is the atomic number or number of protons.

2. Cloud of electrons
Floating around the nucleus are the electrons, which areattracted by the protons through electromagnetic energy . This part is also called the cortex. Interestingly, an atom always has the same number of protons as electrons, so they are said to be electrically neutral.
According to scientists, the electrons orbit around the nucleus following a circular or elliptical orbit (they are called electronic shells or levels), at the same time that they rotate on themselves. The outer shell of electrons is also called the valence shell, and the atom’s probability of producing a chemical reaction depends on them.

Properties of an Atom
Finally, we review each and every one of the properties of an atom.

1. Mass
As we have said, all the mass of the atom comes frometerminada by the number of protons and neutrons found in the nucleus, and is that the electrons have a much smaller mass. The mass of the atom is so small that it is expressed by the unit of atomic mass (u) or dalton (Da) and its equivalence in kilograms would be 1.660538921 (73) × 10-27

2. Size
An atom reaches as far as its electron cloud ends, but that boundary is not always clear. Unfortunately, the size of an atom cannot be measured exactly, but we can make an approximation if we take into account a physical phenomenon in which it is involved. Several studies indicate that an atom can oscillate between 0.5 and 5 angstroms (A) , and each angstrom is equivalent to 0,000,000,000.1 meters. Very small.

3. Magnetic properties
The magnetism (force of attraction) of each element is determined by the movement of electrons around the nucleus, producing a magnetic field similar to that of a magnet. This has been studied by means of electromagnetic theory, too complex to expose it here as well.

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Bibliographic references
Asimov, I., Cruz, A., & Villena, MI (1975). Brief history of chemistry. Alliance.
Demtroder, W. (2010). Atoms, molecules and photons (p. 194). Heidelberg:: Springer.