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How are covalent bonds shown in structural formulas?
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covalent bond
In polar covalent bonds, such as that between hydrogen and oxygen atoms, the electrons are not transferred from one atom to the other as they are in an ionic bond. Instead, some outer electrons merely spend more time in the vicinity of the other atom. The effect of this orbital distortion is to induce regional net charges that hold the atoms together, such as in water molecules.
In structural formulas, covalent bonds are represented by lines connecting the chemical symbols of the atoms involved. The number of lines used indicates the nature of the bond:12
- Single bond: A single line represents a bond involving one shared electron pair.2
- Double bond: Two lines (=) represent a bond involving two shared electron pairs.12
- Triple bond: Three lines (β‘) represent a bond involving three shared electron pairs.12
These representations, often referred to as Lewis structures in their formal chemical context, illustrate the topological pattern of bonds within a molecule. While these formulas effectively show how atoms are linked, they do not necessarily depict the actual three-dimensional shape of the molecule. In some cases, such as with organic ring structures, bonds may be simplified using polygon conventions where each apex represents a carbon atom.321