Multiple Bonds (HL IB Chemistry)

• Non-metals are able to share more than one pair of electrons to form different types of covalent bonds
• Sharing electrons in the covalent bond allows each of the 2 atoms to achieve an electron configuration similar to a noble gas
  • This makes each atom more stable

• It is not possible to form a quadruple bond as the repulsion from having 8 electrons in the same region between the two nuclei is too great

Covalent Bonds & Shared Electrons Table

Type of covalent bond	Number of electrons shared
Single (C  C)	2
Double (C = C)	4
Triple (C C)	6

Bond energy

• The bond energy is the energy required to break one mole of a particular covalent bond in the gaseous states
  • Bond energy has units of kJ mol^-1

• The larger the bond energy, the stronger the covalent bond is

Bond length

• The bond length is internuclear distance of two covalently bonded atoms
  • It is the distance from the nucleus of one atom to another atom which forms the covalent bond

• The greater the forces of attraction between electrons and nuclei, the more the atoms are pulled closer to each other
• This decreases the bond length of a molecule and increases the strength of the covalent bond
• Triple bonds are the shortest and strongest covalent bonds due to the large electron density between the nuclei of the two atoms
• This increase the forces of attraction between the electrons and nuclei of the atoms
• As a result of this, the atoms are pulled closer together causing a shorter bond length
• The increased forces of attraction also means that the covalent bond is stronger

Diagram to show bond lengths for carbon

Triple bonds are the shortest covalent bonds and therefore the strongest ones