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ValenceFilling

is an option for Molecule that specifies whether to fill open valences with hydrogen atoms.

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Basic Examples  
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ValenceFilling

ValenceFilling

is an option for Molecule that specifies whether to fill open valences with hydrogen atoms.

Details

  • ValenceFillingAutomatic adds the appropriate number of hydrogen atoms for a given atom type.
  • ValenceFillingNone adds no hydrogen atoms.
  • ValenceFilling is relevant for molecules created from lists of atoms and bonds, Molecule[{a1,a2,…},…], and does not apply to molecules created from SMILES strings or Entity objects.

Examples

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Basic Examples  (2)

Oxygen atoms have a default valence of 2, so two hydrogen atoms are added:

Wolfram Language code: Molecule[{Atom["O"]}, {}]//AtomList

Use ValenceFillingNone to disable automatic hydrogen atoms:

Wolfram Language code: Molecule[{Atom["O"]}, {}, ValenceFilling -> None]//AtomList

ValenceFilling has no effect when a molecule is created from an identifier such as an entity or chemical name, since these have no unmet valences:

Wolfram Language code: Molecule["water", ValenceFilling -> #]& /@ {Automatic, None}
Wolfram Language code: SameQ@@%

Possible Issues  (2)

Molecule will interpret a string as the SMILES string. For example "N" is the SMILES string for ammonia:

Wolfram Language code: Molecule["N"]

Since this molecule has all valences met, ValenceFilling has no effect:

Wolfram Language code: Molecule["N", ValenceFilling -> None]

To create a molecule with a single nitrogen without hydrogens, pass in a list of atoms:

Wolfram Language code: Molecule[{"N"}, {}, ValenceFilling -> None]

A molecule created from a chemical Entity or a chemical name represents a molecule with filled valences. ValenceFilling as an option to Molecule will not suppress hydrogen atoms:

Wolfram Language code: MoleculeValue[ Molecule["3-methoxybenzoic acid", ValenceFilling -> None], "AdjacencyMatrix"]

Instead, give the option IncludeHydrogensNone to MoleculeValue to find the hydrogen-suppressed adjacency matrix:

Wolfram Language code: MoleculeValue[ Molecule["3-methoxybenzoic acid"], "AdjacencyMatrix", IncludeHydrogens -> None]
Wolfram Research (2020), ValenceFilling, Wolfram Language function, https://reference.wolfram.com/language/ref/ValenceFilling.html.

Text

Wolfram Research (2020), ValenceFilling, Wolfram Language function, https://reference.wolfram.com/language/ref/ValenceFilling.html.

CMS

Wolfram Language. 2020. "ValenceFilling." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/ValenceFilling.html.

APA

Wolfram Language. (2020). ValenceFilling. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/ValenceFilling.html

BibTeX

@misc{reference.wolfram_2026_valencefilling, author="Wolfram Research", title="{ValenceFilling}", year="2020", howpublished="\url{https://reference.wolfram.com/language/ref/ValenceFilling.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_valencefilling, organization={Wolfram Research}, title={ValenceFilling}, year={2020}, url={https://reference.wolfram.com/language/ref/ValenceFilling.html}, note=[Accessed: 13-June-2026]}