Yes. Two atoms sharing electroncs in a covalent bond is a chemical reaction.
The type of chemical reaction that occurs when 2 atoms are joined by a covalent bond is a synthesis reaction. In this reaction, two or more substances combine to form a new compound by sharing electrons between atoms to form the covalent bond.
Chemical bonds are formed by sharing of atoms.
It is not clear from your question what you mean by sharing substances, or exactly what it is that these substances are sharing. However, I'll make a guess. Chemical reactions often involve atoms sharing electrons. And what happens to them during chemical reactions is that the distribution of electrons shifts. Electrons don't have to actually leave one atom and go to another in order to form a chemical reaction. Sometimes it is more a matter of spending some time with one atom and some time with another, or with several others. Electrons are very versatile.
Bonds are broken by rearrangement of electrons, and then new bonds are made, again by rearrangement (sharing, donating, etc) of electrons.
Chemical bonds are formed by the sharing or donating of electrons. The electrons that atoms use to make chemical bonds are the outermost electrons, also known as valence electrons.
transferring or sharing electrons
Gain, or loss, or sharing of electrons with other atoms.
In a chemical reaction, it is the outer electrons of atoms that interact with each other. These outer electrons are involved in forming chemical bonds between atoms, which ultimately results in the formation of new substances.
A chemical reaction
Electrons!
chemical bond
No, different atoms make chemical bonds in different ways. They may form chemical bonds by either loosing or accepting electrons, sharing or by mutual sharing electrons.