Drawing and checking
Organic chemistry is a drawing subject. The first tool is paper. Software is useful when it lets you repeat the same check you should already be doing by hand: count atoms, find the electronegative atom, look at the 3D shape, or confirm a molar mass.
What to practise, not what to collect
| Skill on the page | What “done” looks like | A reasonable check |
|---|---|---|
| See a functional group | You can draw it from memory and name the nucleophilic / electrophilic site | Paper, then any structure editor |
| Rank acidity | You can point at electronegativity, resonance, and hybridization without a table | Acid–base lesson + a periodic table |
| Push arrows | Every arrow starts at electrons and ends at an atom or bond | Redraw; do not stare at a 3D model first |
| Mass / moles | You can convert mass ↔ moles with the correct molar mass | A calculator after you wrote the equation |
Structure editors and 3D views
Desktop chemists often draw 2D structures in ChemDraw or a free 2D sketcher such as Ketcher. For 3D views of a structure you already have, use Mol* or VMD (VMD is a molecular viewer, not a 2D editor). PubChem is the usual place to look up a name, SMILES, or 3D conformer. On a phone or tablet, a touch editor such as MolSketchGo can do the same classroom job: draw the skeleton, set a charge, and look at a 3D conformer so the wedges you drew are not imaginary. For proteins on iOS, MolTouch is a 3D viewer — useful after you can already name the side chains on paper.
Numbers that support the mechanism
The IUPAC periodic table and the NIST Chemistry WebBook are the usual references for electronegativity, mass, and tabulated data. Element OTG is a pocket table for the same lookup away from a desk. Mole OTG is a mass / mole calculator — use it after you have written the equation. Residue lists such as the NCBI amino-acid table or Amino Acids OTG help before you talk about amide bonds or side-chain acids and bases.
Each name above links to an official page. MolSketchGo, MolTouch, Element OTG, Mole OTG, and Amino Acids OTG are published by Japality Limited, which also maintains JapaLingo.jp.