How to Determine Which Atom to Use As the Central Atom

By Jack Brubaker

Chemists use Lewis dot structures to represent the bonding schemes in molecules. The concept of Lewis structures primarily relies on the octet rule, which states that most atoms prefer eight electrons in their outermost shells. The electrons surrounding each atom can either reside on the atom itself, which chemists refer to as a “lone pair,” or be shared between two atoms. Lewis dot structure provides a remarkably simple and effective method of visualizing bonding schemes, but constructing a proper Lewis structure starts with the identification of the central atom, or the atom to which most of the other atoms bond.