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Anonymous asked in Science & MathematicsChemistry · 1 month ago

Molecule structure?

How can you construct a model of a molecule based on a chemical formula?

2 Answers

  • Huh
    Lv 6
    1 month ago

    Typically, you can't. 

    If for example, my molecule is C_(3349)H_(5308)N_(878)O_(976)_(S17),

    where underscores denote subscripts, tell me where every atom is? (That is actually a protein I am working on.)

    Tell me where every atom is. You can't tell me. You can't even guess. 

    The structure of this protein has been determined by X-ray crystallography. Trap the molecule in an ordered crystal structure, solve the diffraction pattern. 

    For smaller molecules infrared spectroscopy could be enough to tell you what functional groups are present like carboxyl, amino, etc, groups in the molecule. Nuclear magnetic resonance tells you the magnetic environment of hydrogen atoms in a molecule. So two protons on a nitrogen looks different than 2 protons on a carbon even though they are both protons or hydrogen atoms. 

    For a small molecule like C2H6O, that could be either ethanol or dimethyl ether.

    Those molecules satisfy the conditions that carbon likes to form 4 bonds, hydrogen 1 bond, and oxygen 2 bonds.  

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  • 1 month ago

    It depends on the formula.  Generally speaking you can't.  It's possible, but only if the formula defines a unique molecule, which doesn't happen that often.

    For example, a formula as simple as C3H6O has 12 or 13 (depending on how you count) possible different molecular structures.

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