| Identity | Select any number of elements and/or wildcards. Any (a)!Hydrogen (r)Heteroatom (q) Halide (x)Metal (m) | NOT |
|
| Aromatic (A) | Specifies that the matched atom should be aromatic. Use the NOT modifier to specify not aromatic or anti-aromatic. | NOT |
| Charge (C) | Defines the allowed charge for the matched atom.
| NOT |
| Hydrogens (H) | Defines the total number of hydrogens attached to the atom, implicit and explicit.
| NOT |
| Ring Count (R) | Defines the total number of rings this atom is a member of. (SSSR)
| NOT |
| Saturation (S) | Specifies that the matched atom should be saturated. Use the NOT modifier to specify unsaturation. | NOT |
| Connectivity (X) | Defines the total number of bonds connected to the atom, including all hydrogens.
| NOT |
| Connectivity (No H) (x) | Defines the total number of bonds connected to the atom, excluding all hydrogens.
| NOT |
| Chirality (@) | Defines the stereochemical configuration of the atom. | NOT |