Chemical bond
Introduction
A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the electrostatic force of attraction between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds. The strength of chemical bonds varies considerably; there are "strong bonds" or "primary bonds" such as covalent, ionic and metallic bonds, and "weak bonds" or "secondary bonds" such as dipole–dipole interactions, the London dispersion force and hydrogen bonding.
Types of Chemical Bonds
Covalent Bonds
A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding.
Ionic Bonds
An ionic bond is a type of chemical bond that involves the electrostatic attraction between oppositely charged ions, and is the primary interaction occurring in ionic compounds. The ions are atoms that have gained one or more electrons (known as anions, which are negatively charged) and atoms that have lost one or more electrons (known as cations, which are positively charged).
Metallic Bonds
A metallic bond is a type of chemical bond that exists between atoms of metallic elements. It involves the sharing of many detached electrons, which, for these atoms, it is often described as a mixture of ionic and covalent bonding.
Bonding Mechanisms
Chemical bonds are the result of a variety of different mechanisms. These include the electrostatic attraction between positive and negative charges, the sharing of electrons between atoms, and the attraction of positively charged protons in the nucleus for negatively charged electrons in the electron cloud.
Bond Strength and Length
The strength of a chemical bond is determined by the energy required to break it. This is known as bond dissociation energy. The length of a chemical bond is the average distance between the nuclei of two bonded atoms.
Chemical Bonding Theories
Chemical bonding theories provide a way to describe how electrons are distributed in molecules and how that distribution affects the chemical and physical properties of substances. The two most common theories are the valence bond theory and the molecular orbital theory.