Unit III types of bonds

Chemical bonds allow all of the elements to combine in a variety of ways to create everything on Earth. Without these chemical bonds life as we know it would not be able to exist as every living organism is created from compounds of elements that work together in specific ways.

A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The strength of chemical bonds varies considerably; there are "strong bonds" such as covalent or ionic bonds and "weak bonds" such as Dipole-dipole interaction, the London dispersion force and hydrogen bonding.

Since opposite charges attract via a simple electromagnetic force, the negatively charged electrons that are orbiting the nucleus and the positively charged protons in the nucleus attract each other. An electron positioned between two nuclei will be attracted to both of them, and the nuclei will be attracted toward electrons in this position. This attraction constitutes the chemical bond. A chemical bond is a region that forms when electrons from different atoms interact with each other. The electrons that participate in chemical bonds are the valence electrons, which are the electrons found in an atom's outermost shell.

In general, strong chemical bonding is associated with the sharing or transfer of electrons between the participating atoms. The atoms in molecules, crystals, metals and diatomic gases are held together by chemical bonds, which dictate the structure and the bulk properties of matter. The number of bonds an atom forms corresponds to its valence. The amount of energy required to break a bond and produce neutral atoms is called the bond energy. All bonds arise from the attraction of unlike charges according to Coulomb's law. The principal types of a chemical bond are the ionic, covalent, metallic, and hydrogen bonds. The ionic and covalent bonds are idealized cases, however; most bonds are of an intermediate type.

Ionic Bonds

An ionic bond is formed when one atom accepts or donates one or more of its valence electrons to another atom. These chemical bonds are created between ions where one is a metal and one is a non-metal element. When an atom (or group of atoms) gains or loses one or more electrons, it forms an ion. Ions have either a net positive or net negative charge. Positively charged ions are attracted to the negatively charged 'cathode' in an electric field and are called cations. Anions are negatively charged ions named as a result of their attraction to the positive 'anode' in an electric field. Every ionic chemical bond is made up of at least one cation and one anion.

The atoms of metallic elements, e.g., those of sodium, lose their outer electrons easily, while the atoms of nonmetals, e.g., those of chlorine, tend to gain electrons. The highly stable ions that result retain their individual structures as they approach one another to form a stable molecule or crystal. Sodium chloride (NaCl) is the classic example of ionic bonding

Ionic bonding is not limited by simple binary systems, however. An ionic bond can occur at the center of a large covalently bonded organic molecule such as an enzyme. In this case, a metal atom, like iron, is both covalently bonded to large carbon groups and ionically bonded to other simpler inorganic compounds (like oxygen).

Ionic bonds form many compounds every day.