bond length

Examples of bond length in the following topics:

• Bond Lengths

  • The distance between two atoms participating in a bond, known as the bond length, can be determined experimentally.
  • The bond length is the average distance between the nuclei of two bonded atoms in a molecule.
  • Bonds lengths are typically in the range of 1-2 Å, or 100-200 pm.
  • Even though the bond vibrates, equilibrium bond lengths can be determined experimentally to within ±1 pm.
  • For example, the bond length of $C - C$ is 154 pm; the bond length of $C = C$ is 133 pm; and finally, the bond length of $C \equiv C$ is 120 pm.

• Physical Properties of Covalent Molecules

  • The Lewis bonding theory can explain many properties of compounds.
  • Lewis theory also accounts for bond length; the stronger the bond and the more electrons shared, the shorter the bond length is.
  • According to the theory, triple bonds are stronger than double bonds, and double bonds are stronger than single bonds.
  • However, the theory implies that the bond strength of double bonds is twice that of single bonds, which is not true.
  • Discuss the qualitative predictions of covalent bond theory on the boiling and melting points, bond length and strength, and conductivity of molecules

• Bond Energy

  • The higher the bond energy, the 'stronger' we say the bond is between the two atoms, and the distance between them (bond length) is smaller.
  • Similarly, the C-H bond length can vary by as much as 4% between different molecules.
  • For this reason, the values listed in tables of bond energy and bond length are usually averages taken over a variety of compounds that contain a specific atom pair.
  • The internuclear distance at which the energy minimum occurs defines the equilibrium bond length.
  • In general, the stronger the bond between two atoms, the lower the energy minimum is and the smaller the bond length.

• Bond Polarity

  • Bond polarity: when atoms from different elements are covalently bonded, the shared pair of electrons will be attracted more strongly to the atom with the higher electronegativity.
  • Such bonds are said to be 'polar' and possess partial ionic character.
  • The dipole moment is calculated by evaluating the product of the magnitude of separated charge, q, and the bond length, r:
  • If two charges of magnitude +1 and -1 are separated by a typical bond length of 100 pm, then:
  • In molecules containing more than one polar bond, the molecular dipole moment is just the vector addition of the individual bond dipole moments.

• Double and Triple Covalent Bonds

  • The double bond between the two carbon atoms consists of a sigma bond and a π bond.
  • A triple bond involves the sharing of six electrons, with a sigma bond and two $\pi$ bonds.
  • Experiments have shown that double bonds are stronger than single bonds, and triple bonds are stronger than double bonds.
  • Double bonds have shorter distances than single bonds, and triple bonds are shorter than double bonds.
  • The bond lengths and angles (indicative of the molecular geometry) are indicated.

• Time to Maturity

  • "Time to maturity" refers to the length of time before the par value of a bond must be returned to the bondholder.
  • "Time to maturity" refers to the length of time that can elapse before the par value (face value) for a bond must be returned to a bondholder.
  • The issuer of a bond has to repay the nominal amount for that bond on the maturity date.
  • The length of time until a bond's matures is referred to as its term, tenor, or maturity.
  • These dates can technically be any length of time, but debt securities with a term of less than one year are generally not designated as bonds.

• Maturity Date

  • The length of time until the maturity date is often referred to as the term or tenor or maturity of a bond.
  • The maturity can be any length of time, although debt securities with a term of less than one year are generally designated money market instruments rather than bonds.
  • Most bonds have a term of up to 30 years.
  • Normally the maturity of a bond is fixed.
  • In this case, the maturity date is the day when the bond is called.

• The Nature of Bonds

  • A bond is an instrument of indebtedness of the bond issuer to the holders.
  • The main categories of bonds are corporate bonds, municipal bonds, and U.S.
  • Bond maturities range from a 90-day Treasury bill to a 30-year government bond.
  • A bond is a form of loan: the holder of the bond is the lender (creditor), the issuer of the bond is the borrower (debtor), and the coupon is the interest.
  • Certificates of deposits (CDs), or short term commercial papers, are considered to be money market instruments and not bonds: the main difference is in the instruments length of term.

• Hybridization in Molecules Containing Double and Triple Bonds

  • sp2, sp hybridizations, and pi-bonding can be used to describe the chemical bonding in molecules with double and triple bonds.
  • Ethene (C2H4) has a double bond between the carbons.
  • The hydrogen-carbon bonds are all of equal strength and length, which agrees with experimental data.
  • The chemical bonding in acetylene (ethyne) (C2H2) consists of sp-sp overlap between the two carbon atoms forming a sigma bond, as well as two additional pi bonds formed by p-p overlap.
  • In ethene, carbon sp2 hybridizes, because one π (pi) bond is required for the double bond between the carbons, and only three σ bonds form per carbon atom.

• Characteristics of Bonds

  • In finance, bonds are a form of debt: the creditor is the bond holder, the debtor is the bond issuer, and the interest is the coupon.
  • Bonds are debt instruments issued by bond issuers to bond holders.
  • The length of time until the maturity date is often referred to as the term or maturity of a bond.
  • High-yield bonds are bonds that are rated below investment grade by the credit rating agencies.
  • Most callable bonds allow the issuer to repay the bond at par.