A covalent bond is a chemical or physical reaction that has two electrically opposite elements attached to one another through an exchange of electrons. Molecules that possess covalent bonding include the covalently bound water molecules (H2O), hydrogen, oxygen, chlorine (CH2), ammonia (NH3), and hydrogen (H). In non-covalently bonded molecules, such as H-atom molecules and polymers, the covalents are invisible; hence, they are called an insulator.

In chemical bonding, atoms are attached to each other through bonding to form a chemical bond. Chemical bonding occurs when one atom has more electrons than another atom. The bonding can occur between two atoms or between multiple atoms that are electrically opposite. The chemical bonds can be strong or weak and can be neutral. The strongest of the covalency is a hydrogen-electron ion bond.

All types of chemical bonds can be broken by applying an energy. The most commonly used methods are electrostatic repulsion and electrostatic attraction. While electrostatic repulsion breaks covalents apart, electrostatic attraction breaks them apart in long chains of identical atoms.

Covalents are extremely useful in chemical reactions. Water is an excellent example of a covalently bound molecule. It plays a crucial role in all biological processes including metabolism, cell respiration, electrolyte homeostasis, and the transmission of nerve impulses. Without water, these various biological processes would not function. Water is essential for all living organisms including plants and animals.

Covalents also play an important role in chemical synthesis. Hydrogen is the most basic covalently bonded substance. The hydrogen atom bonds with an electron in the second position of a hydrogen molecule and produces a molecule containing both hydrogen and an electron. Hydrogen can bond with oxygen to produce an amino acid. {H-atom molecule and is the basis of DNA and RNA. {DNA and RNA are the information carriers in cells. {Nucleic acids carry genetic information. {DNA and RNA are made up of bases {A, which are pairs of nucleotides which are attached to a single strand of DNA. {Nucleic acids carry genetic information.

Covalents can also be formed between two hydrogens and one or more of an amino acid. {H-atom molecule. These are known as isomers. Molecules with only one pair of an isomer have the same composition as water molecules. When two identical molecules of the same amino acid but different hydrogens bind to each other, a covalently bonded molecule is formed. {Covalent bonds between two identical molecules of the same amino acid but different hydrogens bind to each other are called stereoselectively bonded molecules. Covalents may also be formed between two different hydrogens and the same amino acid when one molecule of each molecule is coupled with an electron. This is known as isocyanate bonding. isocyanates are weaker in strength than covalents and are the most common chemical bonds found in nature. These are the most abundant type of covalency and the weakest bonds.

A covalent bond is found in organic, inorganic, and molecular systems. Molecules that are in a covalently bonded state are called ionized. In organic chemistry a covalently bonded system is described as a system of two or more molecules which share electrons in such a way that one of the molecules makes a longer than usual covalently bonded molecule and the other molecule becomes negatively charged.

Molecules can also form covalently bonded structures. Molecules of the same substance are often found in the same structure and this is referred to as homology. Molecules that are similar in chemical composition but with different masses are usually found in different structures. This is referred to as homotopy. Molecules are also found in different structures and can share electrons among themselves in what is known as electroposon bonding. Electroposons are atoms or protons that have been positively charged. {N+ and positively repelled. Molecules are also found in different structures and have similar masses and are called stereoisomers. {E> They are very similar to atoms in their molecular structure.