The laws by which substances are transformed have long remained an unsolved mystery to humans. The classical theory of interatomic bonds was proposed quite late - in 1916. Since then, the ideas of scientists have evolved. Since then, they haven’t discovered anything fundamentally new, and now every schoolchild who at least tries to study knows the types of chemical bonds. For this knowledge, some medieval scholars would sell the soul.
So, there are basic types of chemical bonds and additional ones called weak interactions. Sometimes, however, they become important, for example, in the formation of the protein structure. The main types of chemical bonds include covalent, as well as ionic and metallic.
Let's start with covalent ones. It was for them that Gilbert Lewis proposed his first classical theory of chemical bonding. What is the idea of this scientist, relevant so far? A covalent bond is formed because in a bound form in the system, less energy is obtained from atoms than in atoms alone. And this is important in chemistry. Each system seeks to get rid of the maximum amount of energy. In the process of forming a covalent bond, each of the fused atoms contributes to the creation of the compound. Thus, the external electronic level is filled, particles with a negative charge go "into general use."
Types of chemical bonds are divided into subtypes. For example, a covalent bond is often nonpolar - for example, between atoms of an identical chemical element. So molecules of gases are formed, such as nitrogen, fluorine, hydrogen. The electron pair "in common ownership" is geometrically approximately in the middle. Although this is difficult to talk about, because studies show that the electron path is almost impossible to predict.
Another thing is the bonds between the atoms of different chemical elements. For example, in a bond between fluorine and hydrogen atoms, the total pair is spatially closer to one of the atoms, namely, fluorine. Such a relationship bears the name of the polar.
But atoms are not always “honestly making an equal contribution” to the formation of a contribution. It also happens that one of the atoms provides two electrons at once, and the second - the orbit for this pair, which goes into general use. What is the nature of this compound? Donor-acceptor type of communication. Ammonium ion can be a good example. Three hydrogen atoms participate in ordinary polar covalent bonds, and the remaining free pair of nitrogen electrons can be transferred for sharing with another hydrogen atom. Nevertheless, such a bond is considered covalent, because regions of increased electron density are between atoms.
What other types of chemical bonds exist? An ionic bond exists between particles having different charges. The force of attraction of the elements of this connection depends only on the distance that separates them, but does not depend on the orientation. Where are such connections? First of all, in crystalline substances - alkalis, carbides, salts, nitrides, basic oxides. If the cation and anion are similar in size, then the bond becomes especially stable. Some chemists tend to consider this type of bond an extreme case of polar covalent. But this is a moot point, because the electron density is still not fully approaching the negatively charged cation.
A metal bond is usually very different from other types of chemical bonds. Since it is not only unique chemically, but also a peculiar physical phenomenon. The fact is that the electrons of all atoms participate in the formation of the bond. And their directional movement explains the possibility of high conductivity of electric current in metals. So each atom in the lattice site contributes to the chemical bond.
As it became clear from the description above, the types of chemical bonds differ precisely by the principle of their formation.