AtomCount

AtomCount[mol]

gives the number of atoms in the molecule represented by mol.

AtomCount[mol,patt]

gives the number of atoms in the molecule mol matching the atom pattern patt.

Details and Options

  • Possible forms for patt are:
  • syman atom with atomic symbol sym
    Atom[rules]an atom with properties described by rules
    MoleculePattern["smarts"]an atom matching the SMARTS string "smarts"
    patt1|patt2|…an atom matching any of the patti
  • With the default option setting IncludeHydrogensAll, AtomCount will include implicit hydrogen atoms. Use IncludeHydrogens"ExplicitOnly" to exclude these hydrogens.

Examples

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Basic Examples  (2)

Count the number of atoms in phenol:

Count the number of carbon atoms:

Count the number of non-carbon atoms:

Count the number of carbon atoms with exactly one hydrogen attached:

Count the number of nitrogen atoms inside a ring:

Highlight the cyclic nitrogen using MoleculePlot:

Options  (1)

IncludeHydrogens  (1)

AtomCount will include all atoms by default:

Use IncludeHydrogensNone to exclude the hydrogens, which make up the majority of atoms:

This is equivalent to using a pattern excluding hydrogen atoms:

Properties & Relations  (1)

Because Molecule will try to fill valences with hydrogen atoms, hydrogen atoms will be included in the count even if they were not in the original molecule expression:

To exclude implicit hydrogen atoms, use:

Alternatively, to stop hydrogen atoms from appearing, use the Molecule option ValenceFillingNone:

The resulting molecule contains a single atom with unpaired electrons:

Wolfram Research (2019), AtomCount, Wolfram Language function, https://reference.wolfram.com/language/ref/AtomCount.html (updated 2020).

Text

Wolfram Research (2019), AtomCount, Wolfram Language function, https://reference.wolfram.com/language/ref/AtomCount.html (updated 2020).

CMS

Wolfram Language. 2019. "AtomCount." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2020. https://reference.wolfram.com/language/ref/AtomCount.html.

APA

Wolfram Language. (2019). AtomCount. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/AtomCount.html

BibTeX

@misc{reference.wolfram_2024_atomcount, author="Wolfram Research", title="{AtomCount}", year="2020", howpublished="\url{https://reference.wolfram.com/language/ref/AtomCount.html}", note=[Accessed: 21-December-2024 ]}

BibLaTeX

@online{reference.wolfram_2024_atomcount, organization={Wolfram Research}, title={AtomCount}, year={2020}, url={https://reference.wolfram.com/language/ref/AtomCount.html}, note=[Accessed: 21-December-2024 ]}