Syntax overview

AsciiChem is plain ASCII chemistry. Every construct is something a chemist can type on a standard keyboard. This page is the tour: every construct, one example each, links to the detail pages.

Atoms and elements

H

$\mathrm{H}$

He

$\mathrm{He}$

C

$\mathrm{C}$

Fe

$\mathrm{Fe}$

Uue

$\mathrm{Uu}\text{e}$

Atom reference →

Subscripts (multiplicity)

H_2

${\mathrm{H}}_2$

H_2O

${\mathrm{H}}_2\mathrm{O}$

H_2SO_4

${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$

C_6H_12O_6

${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$

Multi-character subscripts use braces: H_{2a}.

Prefix isotopes — the headline fix

^14C

${}^{14}\mathrm{C}$

^131I

${}^{131}\mathrm{I}$

^238U

${}^{238}\mathrm{U}$

The prefix binds to the following atom. Why this matters →

Charges

Ca^2+

${\mathrm{Ca}}^{2+}$

Cl^-

${\mathrm{Cl}}^{-}$

SO_4^2-

$\mathrm{S}{\mathrm{O}}_4^{2-}$

Fe^3+

${\mathrm{Fe}}^{3+}$

IUPAC canonical form: number-then-sign. +2 is normalised to 2+.

Oxidation states

Fe^(II)

${\mathrm{Fe}}^{\mathrm{II}}$

Fe^(III)

${\mathrm{Fe}}^{\mathrm{III}}$

Mn^(VII)

${\mathrm{Mn}}^{\mathrm{VII}}$

Roman numerals in parens.

Stoichiometric coefficients

2H_2O

$2{\mathrm{H}}_2\mathrm{O}$

3H_2

$3{\mathrm{H}}_2$

10CO_2

$10\mathrm{C}{\mathrm{O}}_2$

Leading digits followed by an element or open bracket.

Groups with multiplicity

Ca(OH)_2

$\mathrm{Ca}{\left(\mathrm{O}\mathrm{H}\right)}_2$

(NH_4)_2SO_4

${\left(\mathrm{N}{\mathrm{H}}_4\right)}_2\mathrm{S}{\mathrm{O}}_4$

[Fe(CN)_6]^4-

$\left[\mathrm{Fe}{\left(\mathrm{C}\mathrm{N}\right)}_6\right]\text{^4-}$

Bracket variants (), [], {} are preserved through round-trip.

Bonds

H-O-H

$\mathrm{H}-\mathrm{O}-\mathrm{H}$

H_2C=CH_2

${\mathrm{H}}_2\mathrm{C}=\mathrm{C}{\mathrm{H}}_2$

HC#CH

$\mathrm{H}\mathrm{C}\equiv \mathrm{C}\mathrm{H}$

Re##Re

$\mathrm{Re}≣\mathrm{Re}$

C>-H

$\mathrm{C}\uparrow \mathrm{H}$

C-<H

$\mathrm{C}\downarrow \mathrm{H}$

NH_3~>BF_3

$\mathrm{N}{\mathrm{H}}_3\to \mathrm{B}{\mathrm{F}}_3$

A~~B

$\mathrm{A}\sim \mathrm{B}$

Eight kinds: single, double, triple, quadruple, wedge, hash, dative, wavy. Bond reference →

Stereochemistry

(R)-CH_3

$\text{(R)-}\mathrm{C}{\mathrm{H}}_3$

(S)-CH(OH)COOH

$\text{(S)-}\mathrm{C}\mathrm{H}\left(\mathrm{O}\mathrm{H}\right)\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{H}$

(E)-CH=CH

$\text{(E)-}\mathrm{C}\mathrm{H}=\mathrm{C}\mathrm{H}$

(Z)-A=B

$\text{(Z)-}\mathrm{A}=\mathrm{B}$

(alpha)-C

$\text{(alpha)-}\mathrm{C}$

(β)-C

$\text{(beta)-}\mathrm{C}$

Markers attach to molecules. Greek alpha/beta typed words are accepted alongside α/β. Stereo reference →

Lewis structures

:O

$\text{:}\mathrm{O}$

::O

$\text{::}\mathrm{O}$

Cl.

$\mathrm{Cl}\text{.}$

O=O..

$\mathrm{O}=\mathrm{O}\text{..}$

Prefix : for lone pairs; suffix . for radical electrons.

Reactions

2H_2 + O_2 -> 2H_2O

$2{\mathrm{H}}_2+{\mathrm{O}}_2\to 2{\mathrm{H}}_2\mathrm{O}$

HCl + NaOH -> NaCl + H_2O

$\mathrm{H}\mathrm{Cl}+\mathrm{Na}\mathrm{O}\mathrm{H}\to \mathrm{Na}\mathrm{Cl}+{\mathrm{H}}_2\mathrm{O}$

N_2 + 3H_2 <=>[Fe][400°C] 2NH_3

${\mathrm{N}}_2+3{\mathrm{H}}_2\underset{\mathrm{Fe}}{\overset{\text{400°C}}{\rightleftharpoons }}2\mathrm{N}{\mathrm{H}}_3$

Four arrow kinds: forward ->, reverse <-, equilibrium <=>, resonance <->. Conditions in [above][below] brackets. Reaction reference →

Reaction cascades

A -> B -> C

$\mathrm{A}\to \mathrm{B}\to \mathrm{C}$

2A -> 2B -> 2C

$2\mathrm{A}\to 2\mathrm{B}\to 2\mathrm{C}$

A <=>[Fe][T] B -> C

$\mathrm{A}\underset{\mathrm{Fe}}{\overset{\mathrm{T}}{\rightleftharpoons }}\mathrm{B}\to \mathrm{C}$

Multi-step chains promote to a single ReactionCascade. Cascade reference →

Electron configurations

1s^2 2s^2

$\text{1s^2 2s^2}$

1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10

$\text{1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10}$

Two or more orbital^occupancy pairs.

Embedded math

`K_c = [P]/[R]`

${\displaystyle K_c=\frac{P}{R}}$

`x^2 + y^2`

${\displaystyle x^2+y^2}$

`rate = k[A]^2[B]`

${\displaystyle rate=k{\left[A\right]}^2\left[B\right]}$

Backtick-delimited runs are parsed by Plurimath. Embedded math reference →

Combining constructs

Real chemistry mixes everything:

^14C_6H_12O_6 + 6O_2 -> 6CO_2 + 6H_2O `Delta G = -2870 kJ/mol`

${{}^{14}\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6+6{\mathrm{O}}_2\to 6\mathrm{C}{\mathrm{O}}_2+6{\mathrm{H}}_2\mathrm{O}{\displaystyle \Delta G=-2870k\frac{J}{m}ol}$

A radioactive glucose combustion with embedded thermodynamics.

Where to next?

Per-construct detail

Each syntax page has worked examples and round-trip behaviour. Start with Atoms.

The model

Every construct maps to a model class. See The model for the layer diagram and per-class reference.

Round-trip conformance

The Text formatter is the canonicaliser. See Round-trip conformance.

IUPAC mapping

Every construct’s spelling traced to its IUPAC source. See IUPAC mapping.