Coordinate Bonds (DP IB Chemistry)

Coordinate Bonds

What are coordinate bonds?

• In simple covalent bonds the two atoms involved share electrons

• Some molecules have a lone pair of electrons that can be donated to form a bond with an electron-deficient atom

  • An electron-deficient atom is an atom that has an unfilled outer orbital

• So both electrons are from the same atom

• This type of bonding is called dative covalent bond or coordinate bond

• An example of a dative bond is in an ammonium ion

  • The hydrogen ion, H⁺ is electron-deficient and has space for two electrons in its shell

  • The nitrogen atom in ammonia has a lone pair of electrons which it can donate to the hydrogen ion to form a coordinate bond

Dative covalent bonding ammonium ion

Ammonia (NH₃) can donate a lone pair to an electron-deficient proton (H⁺) to form a charged ammonium ion (NH₄⁺)

• More examples of coordinate bonding can be found in the section on Lewis Structures