Summary
Highlights
Nonpolar Covalent Bonds: Hydrogen Example00:00:00
A bond between two atoms of the same element, like two hydrogen atoms (H-H), is a nonpolar covalent bond because the electrons are shared equally due to identical electronegativity, resulting in an equal pull on electrons.
Polar Covalent Bonds: Carbon-Oxygen Example00:01:02
When two nonmetals bond, like carbon and oxygen, it's typically a covalent bond. To determine if it's polar, compare their electronegativity values. Carbon has an electronegativity of 2.5 and oxygen has 3.5. A difference of 1.0 (greater than 0.5) indicates a polar covalent bond, where electrons are shared unequally. Oxygen, being more electronegative, gains a partial negative charge, and carbon a partial positive charge. Bond polarity is indicated by an arrow pointing towards the more electronegative element.
Ionic Bonds: Sodium Chloride Example00:03:28
Bonds between a metal and a nonmetal, such as sodium and chlorine, are typically ionic bonds. In ionic bonds, electrons are transferred rather than shared. Sodium (metal) transfers its electron to chlorine (nonmetal), resulting in sodium becoming a positively charged cation and chlorine a negatively charged anion. The electrostatic attraction between these opposite charges forms the ionic bond.
Carbon-Hydrogen (C-H) Bonds00:06:52
The bond between carbon (electronegativity 2.5) and hydrogen (electronegativity 2.1) has an electronegativity difference of 0.4. This classifies it as a nonpolar covalent bond. Molecules composed only of carbon and hydrogen, like methane or hexane, are nonpolar molecules and do not dissolve in polar substances like water.
Carbon-Carbon (C-C) Bonds00:07:46
A bond between two carbon atoms is always a nonpolar covalent bond because both atoms have the same electronegativity, leading to a zero difference and equal sharing of electrons.
Oxygen-Hydrogen (O-H) Bonds and Hydrogen Bonding00:08:17
The bond between oxygen (electronegativity 3.5) and hydrogen (electronegativity 2.1) has a difference of 1.4, making it a highly polar covalent bond. This is a special type of polar bond known as a hydrogen bond, formed when hydrogen is directly attached to nitrogen, oxygen, or fluorine. Hydrogen bonds are powerful intermolecular forces, responsible for water's high boiling point. Oxygen assumes a partial negative charge, and hydrogen a partial positive charge.
Lithium-Fluorine (Li-F) Bonds00:09:52
The bond between lithium (a metal) and fluorine (a nonmetal) is an ionic bond. Immediately identifying the elements as a metal and a nonmetal signals an ionic interaction, characterized by a significant electronegativity difference and electron transfer, with lithium becoming a cation and fluorine an anion.