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Definition of the atom and its components

definition of atom

An atom is the smallest thing that can be obtained when splitting matter, and it is neutral in charge; If the atom is split, the components of the atom will have an electrical charge.

The atom is the smallest component of a substance capable of exhibiting chemical properties, as well as the foundation of chemistry.

Definition of atom and its components
Definition of the atom and its components

According to atomic science, atoms are the fundamental building blocks of all matter in the universe. Each element in the periodic table has a unique atomic structure that sets it apart from the rest. Depending on its atomic mass, each element has unique physical properties. The atom has undergone multiple cycles of investigation before reaching the current level of understanding.

components of atom

When you examine the atom more closely, you can see that it is made up of positively charged protons, neutrally charged neutrons, and negatively charged electrons, the number of which is dictated by the type of element. The following is a list of each atom's constituents:


A proton is a subatomic particle with a positive charge that is equal to the charge of an electron. The following are some of its most notable characteristics:

  • It is 1836 times the mass of an electron, with a mass of 1.67262 x 10-27 kg.
  • The atomic number of an element is represented by the number of protons, which also defines the order of the elements in the periodic table.
  • Until the late twentieth century, it was thought that the proton was an elementary particle, meaning that it had nothing inside it and could not be divided. However, elementary particle physicists have discovered the proton's composition, and protons are now classified as baryons, which are particles made up primarily of three elementary particles called quarks.


A neutron is a subatomic particle found in the nuclei of all elements except common hydrogen; it has only one proton in its nucleus, and the following are its most notable properties:

  • Neutrons are devoid of electric charge.
  • It has a mass of 1.67493 x 10-27 kg, which makes it somewhat heavier than a proton, which has a mass of 1839 times that of an electron.
  • Nucleons are protons and neutrons that are confined to the narrow and tight area that makes up 99.9% of an atom's mass, known as the nucleus.
  • The neutron, like the proton, was once thought to be an elementary particle until particle physicists disproved this theory at the turn of the century.
  • Neutrons, like protons, belong to the baryons group, which contains three quarks. It's also worth noting that they keep the nucleus together despite the absence of negative particles inside it, only neutral and positive particles, which are known as the strong nuclear forces, which overcome the repulsion of protons cations with each other and keep the nucleus together.


Electrons are subatomic particles with a negative charge that belongs to the elementary particles. The following are some of the electrons' most notable characteristics:

  • It doesn't contain any ingredients and can't be broken down.
  • An atom is the lightest thing on the planet.
  • The mass of an electron is 9.10938356 x 10-31 kg, and because it is so little, it is not taken into account when determining the mass of an atom.
  • When an electron is taken from its orbit around a nucleus, the atom becomes ionized, and it is termed an ion. Electrons are distributed in different energy levels around the nuclei.
  • In the condition of matter known as plasma, electrons can live freely alongside ions.
  • Electrons are classified as fermions in the classification of elementary particle scientists, and their behavior is defined by the Fermi-Dirac statistic.
  • J.J. Thomson discovered the electron while studying cathode rays, and this finding made a significant contribution to our understanding of atomic structure.
  • Because the nucleus has a positive electric charge and the electrons circling around it have a negative charge, an electric force exists between the nucleus and the electrons, attracting the electrons to the nucleus.

model of an atom

Most substances are made up of molecules, which are relatively easy to separate because molecules are made up of atoms that are linked together by chemical bonds, making them more difficult to separate, and each atom is made up of electrons and a nucleus that is connected by an electrical force, necessitating their separation. Electrons gain so much energy that they can leave their orbits and escape.

Electrons and nucleons (protons and neutrons) are relatively long-lived subatomic particles; that is, their decay takes a long time, in contrast to other subatomic particles, because obtaining them requires a lot of energy, and it only takes a short time for them to decay into other, more stable particles, which form the atomic models.

The most important characteristics of atoms

The qualities and behavior of atoms are determined by a number of important properties. These properties include:

number of atoms

The atomic number is one of the most important properties of atoms; it represents the number of positive charges present in the nucleus, i.e. protons, which is also the number of electrons in a neutral atom, for example, the atomic number of the element carbon is 6, while the atomic number of the element uranium is 92, and since the number of electrons is related to chemical reactions, the atomic number is very important when discussing chemical reactions.

mass of an atom

The number of neutrons in the nucleus affects the atom's mass (in English: atomic mass), but not its chemical properties. For example, a carbon atom with 6 protons and 6 neutrons will have the same chemical properties as the isotope carbon, which has 6 protons and 8 neutrons, and the only difference will be the mass of each of the two isotopes, whereas the mass number of an atom is the sum of the number of protons and.


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