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D8.  STRUCTURAL FORMULAE & DISPLAYED FORMULAE

Not least because of the possibility of isomerism and the increasingly complex molecules that can be assembled with larger numbers of atoms, it is vital that the chemist is able to convey such information both unambiguously and in a succinct fashion.  And so Structural Formulae are required – these often seem to mean different things to different people and so there is little choice but to deal with terminology that may be encountered.

For a molecular entity a structural formula displays all the atoms of its constituent elements joined by lines representing single or multiple covalent bonds without any indication or implication concerning the spatial direction of bonds while depicting their unambiguous connectivity in one molecule.

Except for very simple cases, deducing a structural formula normally requires rather more information than that needed for the molecular formula.  Often specific chemical details about reactivity are necessary or information from spectroscopic techniques like IR & NMR.

The various representations for the alkane ethane that are shown below serve to illustrate the differences.

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