What are the factors on which bond length depends?

2 Answers

krishna-agrawala's profile pic

krishna-agrawala | College Teacher | (Level 3) Valedictorian

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Bond length is the distance between centers of atoms bonded within a molecule. bond length is measured in units of picometers (pm) which is equal to 10^-12 meters. Bond length depends on three main factors.

  1. Size of atoms: smaller atoms have lower bond length. The lowest bond length is between two atoms of the hydrogen, which has the smallest atom size. The bond length of H-H bond is 74 pm.
  2. Bond strength: stronger bonds tend to have lower bond length as compared to weaker bonds.
  3. Multiplicity of bonds: Multiply bonds tend to have lower bond lengths as compared to single ply bonds
radnor's profile pic

radnor | Student, College Freshman | eNotes Newbie

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a) Size of atoms – Bond length increases with the increase in size of the

atoms e.g. bond length between H & Cl in HCl = 127 pm whereas bond

length between C & Cl, C — Cl = 177 pm.

b) Nature of bonds – Bond length decreases with the multiplicity of

bonds because attractive forces between electrons and nuclei will

increase with the increase in number of shared electrons between

bonded atoms e.g. in C — C , bond length is 154 pm whereas in C ═ C

bond length is 134 pm.

3) Bond angle – As we know that the molecules formed by covalent bond are

oriented in a specific direction. As a result the atoms of these molecules

develop a bond angle.

The bond angle is defined as the average angle between the orbitals

containing bonding electron pairs around the central atom in a molecule. It is

expressed in degree / minute / second. It helps in determining the shape of

the molecules because it gives an idea about the distribution of orbitals

around the central atom in a molecule.