Definition
A chemical bond formed when two atoms share one or more pairs of electrons, holding the atoms together as a molecule. Covalent bonds typically form between nonmetal atoms and produce stable molecules such as water, oxygen, and the hydrocarbons that make up aviation fuels and lubricants.
Plain English
Two atoms hold onto each other by sharing electrons between them, like two people holding the same rope. The shared electrons keep the atoms locked together as a single molecule.
Context Anchor
Seen in aviation maintenance chemistry when discussing fuels, plastics, rubber, composite materials, sealants, and other compounds used on aircraft.
Derivation
From the Latin co- meaning 'together' and valent from valere, 'to be strong.' A covalent bond is literally a 'strength shared together' — the atoms are strong because they share.
Why Pilots Care
For pilots this is usually background knowledge, but in maintenance and systems study it helps explain why materials such as fuel, rubber, plastics, and sealants behave the way they do.
Analogy
Think of two people holding the same rope between them. Neither person owns the whole rope alone, but sharing it connects them.
Grounding Statement
In a covalent bond, atoms stay together because the shared electrons help hold both atoms in place.
Intuition Check
Do not think of a covalent bond as glue between atoms. The bond is the attraction created when atoms share electrons.
Example Sentence 1
The hydrocarbon molecules in avgas are held together by covalent bonds between carbon and hydrogen atoms.
Example Sentence 2
The covalent bonds in hydrocarbon fuels allow them to release energy when they react with oxygen during combustion.