Glossary of Frequently Used
- Primary Bonds = Chemical (strong) Bonding
i.e., ionic, covalent or metallic bonds.
- Secondary Bonds = Physical (weak) Bonding
i.e., hydrogen and van der Waals bonds.
- Directional Bonds = Multiple bonds that
are localized and occur at fixed angles with
respect to each other.
- Covalent Bonds = The attainment of
the "magical octet" of outer electrons by
atoms sharing pairs of valence electrons.
- Each shared pair constitutes a single bond
- Covalent bonds are directional
- Ionic Bonds = The establishment of the "Noble
Gas Configuration" by electron transfer from metallic
atoms to non-metallic atoms.
- The electro-static bond is thus formed between
positively charged metallic ions (cations) and
negatively charged non-metallic ions (anions).
- Metallic Bonds = The bonds formed between an
array of positively charged metallic cations and a "sea"
of negatively charged electrons, the latter being donated
from the outer shells of the constituent atoms.
- Metallic bonds are non-directional.
- Hydrogen Bonds = Weak, secondary bonds
formed by the attraction of polar molecules.
- A polar molecule (or dipole) results from a
permanent imbalance in the electron distribution
in a molecule, e.g., between an electro-negative
atom (oxygen)and an electro-positive atom (hydrogen).
- Van der Waals Bonds = Weak, secondary bonds formed
by the attraction of fluctuating dipoles between atoms of
the noble gases.
- Van der Waals bonds are non-directional.