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4.2 Types of chemical bonds

The covalent bond is a chemical bond arising from the socialization of the

electron pair by the exchange mechanism, when each of the atoms supplies one

electron, or by a donor-acceptor mechanism, if the electron pair is shared to use by

one atom (donor) to another atom (acceptor). There are covalent non-polar and

polar bonds.

The ion bond is a special type of covalent bond which is characterized by a

common electron pair completely owned by a more electronegative atom.

The metallic bond arises from the partial delocalization of valence electrons

which move freely in the metal lattice, electrostatically interacting with positively

charged ions.

According to the method of valence bonds (MVB), a chemical bond is formed

when orbitals overlap, and there valence electrons are located. Here are the
possible ways of some orbitals overlapping:

This method of overlapping is called σ-bond - the overlap area lies on the line

that connects the centers of the atoms.

Another way of overlapping orbitals is

which is called π-bond - the overlap area lies on both sides of the line that connects

the centers of the atoms.

To explain the equivalence of bonds in molecules when inequivalent s-s and s-

2
3
p-orbitals overlap the concept of sp-, sp -, sp -hybridization is introduced.

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