The cells of our body, the air, the water, the different minerals … each of the elements that surround us they are made up of different types of atoms and molecules. These particles are the basic unit of matter and are also used to understand how many biological processes related to neuroscience, such as depolarization, take place.
However, in order to be able to form something as complex as a living organism or the various compounds or materials that we observe in our daily lives, it is necessary that the atoms come together and somehow connect. . Chemistry has studied the composition of matter, including the elements that allow different atoms to bond. These are the so-called chemical bonds.
In this article we will see what are the main types of chemical bonds present in nature.
The chemical bond
Chemical bond is understood like this interaction or force that holds two or more atoms together based on the transmission of electrons between the two.
The electrons in the outermost layers of the atom are attracted to the electrical charge possessed by the atoms around it, especially its nucleus. And although nuclei repel each other by having two positive charges, the electrons (negatively charged) of each of the atoms are attracted by the core of the other.
Depending on the position of the two, the electronegativity or the difficulty of ionizing the atom and the electronic stability that each atom already has, it is possible that the force of attraction between the electron and the nucleus is preventing a repulsion between atoms. A chemical bond will be created in which one of the atoms will lose electrons and the other will gain them, reaching a final state in which the two atoms together will reach a level of stable electric charge.
Main types of chemical bonds between atoms
Below you can see what are the three main types of chemical bonds through which different atoms come together to form different molecules. One of the main differences between them is in the types of atoms which are used (metallic and / or non-metallic, being low electronegative metals and very non-metallic ones).
1. Ionic bond
ionic is one of the most well-known types of chemical bond, Being what is formed when a metal and a non-metal come together (i.e. a component with little electronegativity with one with a lot).
The outermost electron of the metallic element will be attracted to the nucleus of the non-metallic element, giving up the second electron to the first. Stable compounds are formed, the union is electrochemical. In this union, the non-metallic element becomes an anion eventually being negatively charged (after receiving the electron), while the metals become positively charged cations.
A typical example of ionic bonding is found in salt or in crystalline compounds. The materials formed by this type of joint tend to require a large amount of energy to melt and are generally hard, although they can be easily compressed and broken. They generally tend to be soluble and can dissolve easily.
2. Covalent bonds
The covalent bond is a type of bond characterized in that the two atoms to be joined have similar or even identical electronegative properties. Covalent bonding assumes that the two atoms (or more, if the molecule is made up of more than two atoms) share electrons with each other, without losing or gaining in quantity.
These types of bonds are usually part of organic matter, like the one that makes up our body, and are more stable than ionic bonds. Its melting point is lower, So much so that many compounds are in the liquid state, and are generally not electrically conductive. Within covalent bonds we can find several subtypes.
Nonpolar or pure covalent bond
It refers to a type of covalent bond in which two elements are joined with the same level of electronegativity and the union does not cause either part to lose or gain electrons, being atoms of the same element. For example, hydrogen, oxygen or carbon are elements that can join atoms of their own element to form structures. They are not soluble.
Polar covalent bond
In this type of covalent bond, in fact the most common, the atoms that bind are different elements. Both have similar electronegativity although not identical, with which they have different electric charges. Also in this case, the electrons are not lost in any of the atoms, but are shared.
In this subgroup we also find bipolar covalent bonds, in which there is a donor atom that shares electrons and another or other receptors that benefit from this incorporation.
Things as basic and essential to us as water or glucose are formed from this type of bond.
3. Metal link
In metallic bonds, two or more atoms of metallic elements are joined together. This union is not due to the attraction between the two atoms to each other, but to a cation and electrons which have become free and foreign, which makes it such a thing. The different atoms form a network around these electrons, with repeating patterns. These structures tend to appear as solid and cohesive elements., Deformable but difficult to break.
Likewise, this type of bond is linked to the electrical conductivity of metals, because their electrons are free.
Chemical bonds between molecules
While the main chemical bonds are the above, at the level of the molecule we can find other modalities. Some of the main and best known are as follows.
4. By the forces of Van der Waals
This type of bond occurs between symmetrical molecules and acts according to the attraction or repulsion between molecules or the interaction of ions with molecules. Within this type of union we can find the union of two permanent dipoles, of induced dipoles or between permanent and induced dipoles.
5. Hydrogen bond or hydrogen bond
This type of bond between molecules results in an interaction between hydrogen and another element of high polarity. In these bonds, hydrogen has a positive charge and is attracted to polar electronegative atoms, Generating an interaction or a bridge between the two. This union is considerably weak. An example is found in water molecules.
- Chamizo JA (2006). Models of chemistry, chemical education, 17, 476-482.
- Garcia, A .; Garritz; A. and Chamizo, JA. (2009). Chemical bond. A constructivist approach to his teaching.