eguruchela

Diagonal relationship

A diagonal relationship is said to exist between certain pairs of diagonally adjacent elements in the second and third periods of theperiodic table. These pairs (lithium (Li) and magnesium (Mg), beryllium (Be) and aluminium (Al), boron (B) and silicon (Si) etc.) exhibit similar properties; for example, boron and silicon are both semiconductors, forming halides that are hydrolysed in water and have acidic oxides. Diagonal relationships occur because of the directions in the trends of various properties as you move across or down the periodic table. Many of the chemical properties of an element are related to the size of the atom.

Similarities between Lithium and magnesium:
  • The hardness of lithium and magnesium is higher than the other elements in their respective groups.
  • Chlorides of lithium and magnesium have the capability to be soluble in ethanol.
  • They are lighter when compared to other elements in their groups.
  • Lithium and magnesium react gently with water. The oxides and hydroxides are less soluble.
  • In the presence nitrogen, lithium and magnesium form their respective nitrides.
  • Superoxides are not formed when lithium and magnesium react with excess oxygen.
  • Carbon dioxide and their respective oxides are formed when carbonates of magnesium and lithium are heated.

    • Diagonal relationship