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# The atom in a molecule as a mereological construct in chemistry

## Details

**Authors** Sukumar, N.

**Year** 2012

**Publisher** Foundations of Chemistry

**Kind of work** article

**Discipline** Chemistry

**Secondary disciplines** Philosophy

**Applied** false

[Read it at the publisher](https://doi.org/10.1007/s10698-012-9171-z) 
10.1007/s10698-012-9171-z

## In authors' words

### What they set out to do (purpose)

To discuss consequences and manifestations of a mereology of structured wholes in chemistry, using the atom in a molecule as the case.

### How they did it (methods)

Philosophical essay comparing partitioning schemes for atoms in molecules (Bader's zero-flux surfaces, Hirshfeld's stockholder scheme, and a momentum-space partition).

### What they found (results)

The author argues that classical additive mereology fails for molecules, which are structured wholes; that there is no single uncontroversial definition of an atom in a molecule, since Bader's scheme gives non-overlapping atoms with sharp boundaries while Hirshfeld's gives overlapping atoms with fuzzy boundaries dependent on the chosen reference; and that momentum-space and position-space partitions may be complementary descriptions.

## Commentary

### In short

An essay on how chemists define an atom inside a molecule. Different partitioning schemes draw the atom's boundary differently, and the author argues that molecules are structured wholes that classical part-whole logic does not capture.

### Response

The case shows part-whole structure (S) in which where an atom ends depends on the partitioning scheme (D), and in which position-space and momentum-space partitions function as complementary vantage points (P). Caveats: the paper's own framework is process structural realism, the perspective reading is an interpretation of 'complementary descriptions', and the account was taken from the postprint text as summarized, not read in full by the compiler.

**Patterns it shows** D, S, P

Shows the structure is there

**Added** 2026-10-16

**How to cite this** Sukumar, N. (2012). The atom in a molecule as a mereological construct in chemistry. Foundations of Chemistry.