Draw a molecule here.
Click once for a bond, click the end of a bond to grow a chain, drag to aim a bond, click a bond to make it double.
Click once for a bond, click the end of a bond to grow a chain, drag to aim a bond, click a bond to make it double.
Molecule
Nothing drawn yet.
Conformation
Draw a six-membered ring to see chair analysis and a ring flip.
Exercise: count the gauche interactions
Draw a molecule with at least four carbons in a row.
Drawing hotkeys
Hover an atom and type C N O S F L=Cl B=Br H to change it, or a digit 1–9 to add a chain of that many carbons (as in ChemDraw).
Hover a bond and type 1 2 3 for its order, W wedge, D hash. Delete removes what is under the cursor. Esc returns to the arrow tool. ⌘Z undo.
Ideal geometry used in the model
| C–C | 1.54 Å |
| C–H | 1.09 Å |
| C=C / C≡C | 1.34 / 1.20 Å |
| C–O / C–N | 1.43 / 1.47 Å |
| C–Cl / C–Br / C–F | 1.79 / 1.94 / 1.38 Å |
| sp3 angles | 109.47° |
| sp2 / sp angles | 120° / 180° |
| sp3–sp3 dihedrals | ±60° / 180° |
Saturated molecules are placed on the diamond lattice, which makes every value above exact; among all lattice placements the page picks the one with the fewest gauche interactions and no 2.5 Å clashes, so chains come out anti and rings come out as chairs with the bulkier groups equatorial. Alkenes, alkynes and rings smaller than six are built from closed-form geometry; whatever cannot be ideal is listed in the header badge.
How the atoms are numbered
The page renumbers after every edit, the way an introductory IUPAC name would: the parent is the ring if there is one, otherwise the longest carbon chain (one that contains any C=C or C≡C); ties go to the chain with more substituents; numbering runs from the end that gives the multiple bond, then the substituents, the lowest numbers; a remaining tie is settled by reading left to right. Substituent carbons carry the number of the carbon they hang from (C2′, and C2″ one bond further out); heteroatoms on the parent likewise (O2, Cl3). Add a methyl to C2 of hexane and the chain stays C1…C6 with the methyl as C2′; grow a carbon off C1 and the old C1 becomes C2.
Your 3D model appears here as soon as you draw something.
C H
Click atoms to measure.
Newman projection
Click a bond in the drawing (with the arrow tool) or pick one above. Front carbon at the dot, back carbon behind the circle.
Rotate about the bond
–°
Strain at this angle–
Terms–
Closest H···H across the bond–
Textbook additive values (McMurry): H/H eclipsing 1.0, H/C eclipsing 1.4, C/C eclipsing 2.5, gauche C/C 0.9 kcal/mol. Values are quoted only at staggered and eclipsed angles; in between there is no textbook number. Two hydrogens closer than 2.4 Å (their van der Waals contact) are shown in red.
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