Structure 2.4 - Models to Materials
Triangular Bonding Diagram

Unlocking the Mystery of the
Triangular Bonding (Van Arkel) Diagrams:

The Van Arkel-Ketelaar triangle, also known as the Van Arkel-Ketelaar plot, is a graphical representation of the chemical bonding and stability of binary compounds formed between two elements. It was introduced by the Dutch chemists Anton Eduard van Arkel and Jacobus Marinus Ketelaar in the early 20th century.

It is based on electronegativity.

The Van Arkel-Ketelaar triangle is based on the concept of electronegativity, which is a measure of an atom's tendency to attract electrons towards itself in a chemical bond. In the triangle, three elements are chosen as reference points, typically represented as vertices. These reference elements are often chosen as a metal, a non-metal, and a semi-metal or transition metal.

The importance of using
triangular bonding diagrams

The triangle is divided into regions based on the electronegativity values of the elements. Each region represents a specific type of chemical bonding that can occur between the elements. The regions are as follows:

1. Metallic Region: In this region, the electronegativity difference between the two elements is small, indicating that the bonding is predominantly metallic. Metallic bonding occurs when metal atoms share their valence electrons freely, forming a "sea" of delocalized electrons.

2. Ionic Region: In this region, the electronegativity difference between the two elements is large, indicating that the bonding is predominantly ionic. Ionic bonding occurs when there is a transfer of electrons from one element to another, resulting in the formation of positively charged ions (cations) and negatively charged ions (anions).

3. Covalent Region: In this region, the electronegativity difference between the two elements is intermediate, indicating that the bonding is predominantly covalent. Covalent bonding occurs when atoms share electrons in a way that allows them to achieve a stable electron configuration.

The Van Arkel-Ketelaar triangle provides a visual representation of the relationship between electronegativity differences and the type of bonding that occurs between elements. It helps in understanding the general trends and principles governing chemical bonding and stability in binary compounds.