Nonpolar bond
Introduction
A nonpolar bond, also known as a pure covalent bond, is a type of chemical bond where two atoms share a pair of electrons with each other. This bond forms when the electronegativity difference between the two atoms is negligible or zero. In other words, both atoms have an equal or nearly equal pull for the shared electrons, resulting in a balanced distribution of charge.
Characteristics of Nonpolar Bonds
Nonpolar bonds have several defining characteristics that distinguish them from polar bonds. These include:
- Equal Sharing of Electrons: In a nonpolar bond, the two atoms involved share the electrons equally. This is because the electronegativity difference between the two atoms is minimal, leading to a balanced distribution of electron density.
- Symmetrical Molecular Structure: Nonpolar molecules typically have a symmetrical structure. This symmetry means that the molecule's electric charge is evenly distributed, which prevents the formation of partial positive and negative charges.
- Low Polarity: Nonpolar bonds exhibit low polarity due to the equal sharing of electrons between the atoms. This results in a molecule that does not have distinct positive or negative poles.
- Non-Reactivity: Nonpolar molecules are generally less reactive than polar molecules. This is because they do not have distinct positive or negative ends, which are often necessary for chemical reactions to occur.
Formation of Nonpolar Bonds
Nonpolar bonds form when two atoms with similar electronegativities interact. The electronegativity of an atom is a measure of its ability to attract shared electrons in a chemical bond. When two atoms have similar electronegativities, they share the electrons equally, resulting in a nonpolar bond.
For example, in a molecule of oxygen (O2), both oxygen atoms have the same electronegativity. As a result, they share the electrons equally, forming a nonpolar bond. Similarly, in a molecule of methane (CH4), the carbon and hydrogen atoms share electrons equally, resulting in nonpolar bonds.
Examples of Nonpolar Bonds
Nonpolar bonds are common in many molecules, including:
- Diatomic Molecules: Diatomic molecules, such as hydrogen (H2), nitrogen (N2), oxygen (O2), and the halogens (F2, Cl2, Br2, I2), consist of two atoms of the same element. Because the atoms are identical, they have the same electronegativity and share electrons equally, forming nonpolar bonds.
- Hydrocarbon Molecules: Hydrocarbon molecules, such as methane (CH4), ethane (C2H6), and propane (C3H8), consist of carbon and hydrogen atoms. The difference in electronegativity between carbon and hydrogen is small, leading to the formation of nonpolar bonds.
Nonpolar Bonds and Intermolecular Forces
Nonpolar molecules are affected by a type of intermolecular force known as London dispersion forces or Van der Waals forces. These are the weakest type of intermolecular force and occur between all molecules, whether they are polar or nonpolar. However, they are the only type of intermolecular force that occurs between nonpolar molecules.
London dispersion forces arise from temporary fluctuations in electron distribution within molecules. These temporary fluctuations can induce a temporary dipole in a neighboring molecule, leading to a weak attraction between the two molecules. The strength of London dispersion forces increases with the size and shape of the molecules involved.
Applications of Nonpolar Bonds
Nonpolar bonds and the molecules they form have numerous applications in various fields, including:
- Chemistry: Understanding nonpolar bonds is fundamental to understanding chemical reactions, particularly those involving organic compounds. Many organic reactions involve the breaking and forming of nonpolar bonds.
- Pharmaceuticals: Many drugs are nonpolar molecules, which allows them to pass through the lipid bilayer of cell membranes and interact with their target sites.
- Material Science: Nonpolar materials, such as oils and fats, are used in a variety of applications, from cooking to lubrication to waterproofing.