double bond

Thân thiện

A chemist draws a double bond between two carbon atoms on a whiteboard.

Definition

1. Noun:
   • A covalent bond in which two pairs of electrons are shared between two atoms: A "double bond" is a specific type of chemical bond where two atoms are connected by sharing two pairs of valence electrons. It is stronger and shorter than a single bond and restricts the rotation of the bonded atoms.

Usage

• Noun:
  • The carbon-carbon double bond in ethene (C₂H₄) is a classic example.
  • The presence of a double bond in a molecule often makes it more reactive.
  • Oxygen molecules (O₂) are held together by a double bond.

Advanced Usage

• "Conjugated double bonds": A system where double bonds are separated by single bonds in an alternating pattern, which affects the molecule's stability and properties.
  • Beta-carotene, the pigment in carrots, contains a long chain of conjugated double bonds.
• "Coordinate double bond": A specific type of double bond where both shared electron pairs originate from the same atom.
  • In the carbonate ion, one of the C-O bonds can be described as a coordinate double bond.

Variants and Related Words

• Double-bonded (adj): Describing an atom connected by a double bond.
  • The double-bonded carbon atoms are sp² hybridized.
• Pi bond (π bond) (n): One of the two bonds in a double bond, formed by the sideways overlap of p-orbitals.
  • The pi bond in a double bond is weaker than the sigma bond.
• Sigma bond (σ bond) (n): The other bond in a double bond, formed by the head-on overlap of orbitals.
  • The sigma bond provides the primary connection between the two nuclei.

Synonyms

• Unsaturated bond: A general term for double or triple bonds, indicating the presence of pi bonds and fewer hydrogen atoms than a saturated compound.
• Alkene linkage: A term often used in organic chemistry specifically for the carbon-carbon double bond in hydrocarbons.

Related Phrases

• Form a double bond: The process by which a double bond is created.
  • During the reaction, the two carbons form a double bond, releasing a molecule of water.
• Break a double bond: The process of cleaving a double bond, often in a chemical reaction.
  • Ozone is used to break the double bond in alkenes during ozonolysis.

Related Idioms

Học thuật

Noun

1. a covalent bond in which two pairs of electrons are shared between two atoms