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Chemistry: 2,068 3D models

Every element as an atom, orbitals and bonding, crystals, ions and complexes, real compounds from every field of chemistry, substances in their natural form, electrochemistry and lab experiments (real sizes atoms → lab bench). Each one is a ready-made 3D model you can turn, recolour and place in a figure — open BioDioRama and type its name in the Library search.

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Atoms · Transition metals 29 models
Scandium atom (Sc) · Titanium atom (Ti) · Vanadium atom (V) · Chromium atom (Cr) · Manganese atom (Mn) · Iron atom (Fe) · Cobalt atom (Co) · Nickel atom (Ni) …
Atoms · Lanthanides 15 models
Lanthanum atom (La) · Cerium atom (Ce) · Praseodymium atom (Pr) · Neodymium atom (Nd) · Promethium atom (Pm) · Samarium atom (Sm) · Europium atom (Eu) · Gadolinium atom (Gd) …
Atoms · Actinides 15 models
Actinium atom (Ac) · Thorium atom (Th) · Protactinium atom (Pa) · Uranium atom (U) · Neptunium atom (Np) · Plutonium atom (Pu) · Americium atom (Am) · Curium atom (Cm) …
Atoms · Superheavy elements 15 models
Rutherfordium atom (Rf) · Dubnium atom (Db) · Seaborgium atom (Sg) · Bohrium atom (Bh) · Hassium atom (Hs) · Meitnerium atom (Mt) · Darmstadtium atom (Ds) · Roentgenium atom (Rg) …
Orbitals · Atomic orbitals 20 models
1s orbital · 2s orbital · 3s orbital · 2px orbital · 2py orbital · 2pz orbital · The three 2p orbitals together · 3pz orbital …
Bonding · VSEPR molecular shapes 16 models
Linear (AX₂) · Trigonal planar (AX₃) · Bent (from trigonal planar) (AX₂E) · Tetrahedral (AX₄) · Trigonal pyramidal (AX₃E) · Bent (from tetrahedral) (AX₂E₂) · Trigonal bipyramidal (AX₅) · Seesaw (AX₄E) …
Crystals · Bravais lattices 14 models
Cubic primitive (P) lattice · Cubic body-centred (I) lattice · Cubic face-centred (F) lattice · Tetragonal primitive (P) lattice · Tetragonal body-centred (I) lattice · Orthorhombic primitive (P) lattice · Orthorhombic base-centred (C) lattice · Orthorhombic body-centred (I) lattice …
Ions · Monatomic cations 30 models
Hydrogen ion (H⁺) · Lithium ion (Li⁺) · Sodium ion (Na⁺) · Potassium ion (K⁺) · Rubidium ion (Rb⁺) · Caesium ion (Cs⁺) · Beryllium ion (Be²⁺) · Magnesium ion (Mg²⁺) …
Natural forms · Metals 26 models
Sodium metal under oil · Potassium metal under oil · Lithium metal under oil · Calcium metal granules · Magnesium ribbon · Aluminium foil · Iron filings · Copper wire coil …
Natural forms · Elements 15 models
Silicon wafer · Silicon (polycrystalline lumps) · Germanium chunk · Sulfur lumps · Sulfur powder (flowers of sulfur) · Iodine crystals · Red phosphorus · White phosphorus under water …
Natural forms · Salts & crystals 30 models
Table salt (sodium chloride crystals) · Rock salt (halite) · Sugar (sucrose crystals) · Copper(II) sulfate crystals (blue vitriol) · Potassium permanganate crystals · Potassium dichromate crystals · Potassium chromate crystals · Potash alum crystals (octahedral) …
Natural forms · Powders & solids 14 models
Washing soda (sodium carbonate) · Chalk sticks (calcium carbonate) · Silica gel beads (indicating) · Copper(II) carbonate powder · Iron(III) oxide (rust) · Chromium(III) oxide (green) · Lead(II) iodide (golden) · Prussian blue pigment …
Natural forms · Liquids 14 models
Concentrated nitric acid · Bleach (sodium hypochlorite) · Hydrogen peroxide solution · Copper(II) sulfate solution · Potassium permanganate solution · Iron(III) chloride solution · Nickel(II) chloride solution · Cobalt(II) chloride solution …
Natural forms · Medicines (dosage forms) 15 models
Tablets in a blister pack (drug, your label) · Tablets (loose) (drug, your label) · Capsules (drug, your label) · Soft-gel capsules (drug, your label) · Powder (sachet) (drug, your label) · Syrup / oral liquid (drug, your label) · Injection (vial and syringe) (drug, your label) · Ampoules (drug, your label) …
Lab experiments · Reactions & qualitative tests 17 models
Precipitate colours (test-tube rack) · Transition-metal ion colours (test-tube rack) · Silver mirror test (Tollens’) · Benedict’s test for reducing sugars · Spotting tile tests (iodine, biuret, indicators) · Bromine water test for alkenes · Displacement: zinc in copper sulfate · Silver tree (copper in silver nitrate) …
Electrochemistry · Electrodes, cells & batteries 19 models
Standard hydrogen electrode (SHE) · Saturated calomel electrode (SCE) · Silver/silver chloride reference electrode · Glass pH electrode (cut-away) · Lead–acid battery (cut-away) · Alkaline AA cell (cut-away) · Zinc–carbon (Leclanché) cell, cut-away · Button cell (cut-away) …
Organic · Reagents for synthesis 61 models
n-butyllithium / tert-Butyllithium · Sodium triacetoxyborohydride · Diisobutylaluminium hydride · Lithium diisopropylamide · Lithium bis(trimethylsilyl)amide · Dicyclohexylcarbodiimide · N,N'-diisopropylcarbodiimide · HATU …
Organic · Organometallics 36 models
Dimethylzinc / Dimethylmercury · Ferrocene · Ruthenocene · Cobaltocene · Nickelocene · Chromocene · Bis(benzene)chromium · Iron pentacarbonyl …
Industrial · Dyes, pigments & indicators 41 models
Cadmium yellow / Vermilion · Thymolphthalein · Bromocresol green · Methyl red · Methyl violet · Malachite green · Eriochrome black T · Murexide …
Inorganic · Oxides & peroxides 34 models
Iron(II) oxide / Copper(II) oxide / Cobalt(II) oxide and 3 more · Calcium oxide / Barium oxide / Beryllium oxide and 1 more · Sodium oxide / Lithium oxide · Sodium peroxide / Lithium peroxide · Chromium(III) oxide / Yttrium oxide / Manganese(III) oxide and 1 more · Chromium trioxide / Tungsten trioxide / Molybdenum trioxide · Zirconium dioxide / Hafnium dioxide / Ruthenium dioxide and 1 more · Gadolinium oxide / Europium oxide / Lanthanum oxide and 1 more …
Inorganic · Halides & interhalogens 65 models
Caesium chloride / Sodium fluoride / Potassium fluoride and 2 more · Sodium bromide / Potassium bromide · Sodium iodide / Potassium iodide / Caesium iodide · Calcium fluoride / Barium chloride / Beryllium chloride · Aluminium chloride / Aluminium fluoride · Copper(II) chloride / Zinc chloride / Mercury(II) chloride and 5 more · Copper(I) chloride / Silver chloride · Titanium tetrachloride / Vanadium tetrachloride …
Inorganic · Hydrides, nitrides, carbides & chalcogenides 45 models
Tungsten disulfide / Iron disulfide · Cadmium telluride / Zinc telluride · Mercury(II) sulfide / Copper(II) sulfide / Iron(II) sulfide · Silane · Disilane · Phosphine · Silicon nitride · Silicon carbide …
Inorganic · Salts — sulfates, nitrates & carbonates 44 models
Magnesium sulfate / Strontium sulfate · Zinc sulfate / Iron(II) sulfate / Nickel(II) sulfate and 3 more · Sodium nitrate / Potassium nitrate / Lithium nitrate · Sodium nitrite / Potassium nitrite · Sodium carbonate / Potassium carbonate / Caesium carbonate · Magnesium carbonate / Barium carbonate / Strontium carbonate · Copper(II) carbonate / Zinc carbonate / Iron(II) carbonate and 3 more · Sodium sulfate …
Inorganic · Salts — phosphates, halates, oxoanions & others 67 models
Sodium dihydrogen phosphate / Monopotassium phosphate · Sodium chlorate / Potassium chlorate · Sodium perchlorate / Potassium perchlorate / Lithium perchlorate · Sodium bromate / Potassium bromate · Sodium acetate / Potassium acetate · Tripotassium phosphate · Dipotassium phosphate · Triammonium phosphate …
Inorganic · Polyatomic ions 46 models
Permanganate / Chromate / Manganate · Sulfate · Sulfite · Thiosulfate · Hydrogen sulfate · Nitrate · Nitrite · Ammonium …
Inorganic · Minerals & gemstones 35 models
Siderite / Smithsonite · Dolomite · Malachite · Azurite · Spinel · Chromite · Almandine · Beryl …
Inorganic · Elements, allotropes & gases 14 models
Deuterium / Tritium · Buckminsterfullerene · Fullerene C70 · Deuterium oxide · Tritiated water · Carbyne · Fullerene C20 · Alpha-iron …
Materials chemistry · Solids, frameworks & nanomaterials 26 models
Strontium titanate / Calcium titanate · Lead zirconate titanate · Zeolite A · MOF-5 · HKUST-1 · ZIF-8 · 2-aminoterephthalic acid · Porphyrin …
Organic · Alkanes & cycloalkanes 36 models
Ethane · Propane · Butane · Isobutane · Pentane · Isopentane · Neopentane · 2-methylpentane …
Organic · Alkenes, dienes & alkynes 38 models
Propene · 1-butene · Cis-2-butene · Trans-2-butene · Isobutylene · 1-pentene · 1-hexene · Cyclohexene …
Organic · Aromatic hydrocarbons & PAHs 43 models
o-xylene · m-xylene · p-xylene · Ethylbenzene · Cumene · Mesitylene · Durene · Hexamethylbenzene …
Organic · Haloalkanes & aryl halides 45 models
Chloromethane · Carbon tetrachloride · Bromomethane · Iodomethane · Fluoromethane · Chloroethane · Bromoethane · Iodoethane …
Organic · Alcohols & diols 34 models
1-propanol · 1-butanol · 2-butanol · Isobutanol · tert-Butanol · 1-pentanol · 1-hexanol · 1-octanol …
Organic · Phenols 24 models
o-cresol · m-cresol · p-cresol · Resorcinol · Pyrogallol · Phloroglucinol · 4-nitrophenol · 2-nitrophenol …
Organic · Ethers, epoxides & acetals 30 models
Dimethyl ether · Diethyl ether · Diisopropyl ether · Methyl tert-butyl ether · Anisole · Phenetole · Diphenyl ether · 2-methyltetrahydrofuran …
Organic · Aldehydes 26 models
Acetaldehyde · Propionaldehyde · Butyraldehyde · Isobutyraldehyde · Valeraldehyde · Hexanal · Octanal · Decanal …
Organic · Ketones 34 models
Butanone · 2-pentanone · 3-pentanone · Methyl isobutyl ketone · Cyclopentanone · Cyclohexanone · Cycloheptanone · Acetophenone …
Organic · Esters, lactones & anhydrides 39 models
Methyl formate · Ethyl formate · Methyl acetate · Propyl acetate · Butyl acetate · Isoamyl acetate · Benzyl acetate · Vinyl acetate …
Organic · Acyl halides, amides & imides 33 models
Acetyl chloride · Benzoyl chloride · Oxalyl chloride · Propionyl chloride · Chloroacetyl chloride · Phosgene · Acetyl bromide · Formamide …
Organic · Amines & ammonium compounds 49 models
Methylamine · Dimethylamine · Trimethylamine · Ethylamine · Diethylamine · Triethylamine · Isopropylamine · Diisopropylamine …
Organic · Nitriles, nitro, azo & azide compounds 35 models
Propionitrile · Benzonitrile · Malononitrile · Adiponitrile · Succinonitrile · Cyanogen · Hydrogen cyanide · Trichloroacetonitrile …
Organic · Sulfur, phosphorus & silicon compounds 40 models
Methanethiol · Ethanethiol · 1-butanethiol · Thiophenol · Benzyl mercaptan · Dimethyl sulfide · Diethyl sulfide · Dimethyl disulfide …
Organic · Heterocycles (five-membered) 35 models
Furan · Thiophene · Pyrrole · Pyrazole · Oxazole · Isoxazole · Thiazole · Isothiazole …
Organic · Heterocycles (six-membered & fused) 40 models
Pyridine · 2-picoline · 3-picoline · 4-picoline · 2,4,6-collidine · Pyridazine · Pyrimidine · Pyrazine …
Organic · Catalysts & ligands 33 models
Tetrakis(triphenylphosphine)palladium(0) · Palladium(II) acetate · Bis(triphenylphosphine)palladium(II) dichloride · Tris(dibenzylideneacetone)dipalladium(0) · 1,1'-bis(diphenylphosphino)ferrocene · BINAP · XPhos · SPhos …
Organic · Stereochemistry & isomers 16 models
D-alanine · (S)-lactic acid · L-glucose · Glyceraldehyde ((R) / (S)) · Carvone ((R) / (S)) · Limonene ((R) / (S)) · Thalidomide ((R) / (S)) · Ibuprofen ((R) / (S)) …
Industrial · Petrochemicals, fuels & propellants 26 models
Cumene hydroperoxide · Ethyl tert-butyl ether · tert-Amyl methyl ether · Methyl oleate · Methyl linoleate · Methyl palmitate · Squalane · Pristane …
Industrial · Monomers & polymer chemistry 36 models
Vinylidene chloride · Vinylidene fluoride · Tetrafluoroethylene · Hexafluoropropylene · Chloroprene · 2-hydroxyethyl acrylate · Butyl acrylate · 2-ethylhexyl acrylate …
Industrial · Fragrances & flavours 42 models
Ethyl vanillin · Anethole · Isoeugenol · Nerol · Alpha-ionone · Beta-ionone · Beta-damascone · Muscone …
Industrial · Pesticides & herbicides 51 models
DDT · Dieldrin · Aldrin · Chlordane · Lindane · Heptachlor · Endosulfan · Parathion …
Environmental · Pollutants & atmospheric chemistry 40 models
Sulfur dioxide · Sulfur trioxide · Dichlorodifluoromethane · Trichlorofluoromethane · Chlorodifluoromethane · 1,1,1,2-tetrafluoroethane · 2,3,3,3-tetrafluoropropene · Nitrogen trifluoride …
Forensic chemistry & toxicology 21 models
Carfentanil · 3,4-methylenedioxymethamphetamine · Phencyclidine · Aconitine · Thallium(I) sulfate · Sarin · Soman · Tabun …
Inorganic · Acids 36 models
Hydrobromic acid · Hydroiodic acid · Sulfuric acid · Sulfurous acid · Nitric acid · Phosphorous acid · Hypophosphorous acid · Pyrophosphoric acid …
Inorganic · Main-group molecules (VSEPR examples) 15 models
Silicon tetrafluoride · Phosphoryl chloride · Sulfuryl fluoride · Thionyl fluoride · Nitrosyl fluoride · Hypofluorous acid · Dioxygen difluoride · Tetraphosphorus decaoxide …
Inorganic · Coordination complexes 57 models
Hexaamminecobalt(III) chloride · Tris(ethylenediamine)cobalt(III) chloride · Potassium ferrioxalate · Tris(bipyridine)ruthenium(II) chloride · Ferroin · Nickel dimethylglyoxime · Copper(II) acetylacetonate · Iron(III) acetylacetonate …
Analytical chemistry · Standards, titrants & test reagents 42 models
Oxalic acid dihydrate · 2-methoxyethanol · Deuterated chloroform · Dimethyl sulfoxide-d6 · Methanol-d4 · Acetone-d6 · Benzene-d6 · Acetonitrile-d3 …
Analytical chemistry · Chromatography, MS & NMR 20 models
Tetrabutylammonium hydrogen sulfate · Octadecyltrichlorosilane · N,O-bis(trimethylsilyl)trifluoroacetamide · N-methyl-N-(trimethylsilyl)trifluoroacetamide · Pentafluorobenzyl bromide · Trimethylsilyldiazomethane · 1,4-dioxane-d8 · Deuterium chloride …
Electrochemistry · Electrolytes, solvents & redox mediators 32 models
Lithium bis(fluorosulfonyl)imide · Lithium bis(oxalato)borate · Lithium difluoro(oxalato)borate · Ethyl methyl carbonate · Fluoroethylene carbonate · Vinylene carbonate · 1,3-propane sultone · Tetraethylene glycol dimethyl ether …
Nuclear & radiochemistry 21 models
Triuranium octoxide · Uranyl nitrate · Uranyl acetate · Fludeoxyglucose (18F) · Technetium (99mTc) sestamibi · Gallium (68Ga) dotatate · Fluciclovine (18F) · Tributyl phosphate …
Green chemistry & catalysis 12 models
Ethyl lactate · Cyrene · 5-hydroxymethylfurfural · Syringol · Sodium percarbonate · Lindlar's catalyst · Fenton's reagent · Glycerol carbonate …
Medicinal chemistry · Classic scaffolds & landmark drugs 13 models
Benzodiazepine · Azetidinone · Thiazolidinedione · 1,4-dihydropyridine · Tetrahydroisoquinoline · Gonane · Estrane · Androstane …

Atoms · Non-metals 7

Hydrogen atom (H) — Hydrogen (H), atomic number 1 — reactive non-metal, period 1. 1 protons, about 0 neutrons in its commonest isotope, and 1 electron in shells 1 (1s¹). Standard atomic weight 1.008. (≈ 0.1 nm across)
Carbon atom (C) — Carbon (C), atomic number 6 — reactive non-metal, period 2. 6 protons, about 6 neutrons in its commonest isotope, and 6 electrons in shells 2, 4 ([He] 2s² 2p²). Standard atomic weight 12.011. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Nitrogen atom (N) — Nitrogen (N), atomic number 7 — reactive non-metal, period 2. 7 protons, about 7 neutrons in its commonest isotope, and 7 electrons in shells 2, 5 ([He] 2s² 2p³). Standard atomic weight 14.007. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Oxygen atom (O) — Oxygen (O), atomic number 8 — reactive non-metal, period 2. 8 protons, about 8 neutrons in its commonest isotope, and 8 electrons in shells 2, 6 ([He] 2s² 2p⁴). Standard atomic weight 15.999. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Phosphorus atom (P) — Phosphorus (P), atomic number 15 — reactive non-metal, period 3. 15 protons, about 16 neutrons in its commonest isotope, and 15 electrons in shells 2, 8, 5 ([Ne] 3s² 3p³). Standard atomic weight 30.974. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Sulfur atom (S) — Sulfur (S), atomic number 16 — reactive non-metal, period 3. 16 protons, about 16 neutrons in its commonest isotope, and 16 electrons in shells 2, 8, 6 ([Ne] 3s² 3p⁴). Standard atomic weight 32.06. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Selenium atom (Se) — Selenium (Se), atomic number 34 — reactive non-metal, period 4. 34 protons, about 45 neutrons in its commonest isotope, and 34 electrons in shells 2, 8, 18, 6 ([Ar] 3d¹⁰ 4s² 4p⁴). Standard atomic weight 78.971. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))

Atoms · Noble gases 6

Helium atom (He) — Helium (He), atomic number 2 — noble gas, period 1. 2 protons, about 2 neutrons in its commonest isotope, and 2 electrons in shells 2 (1s²). Standard atomic weight 4.0026. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Neon atom (Ne) — Neon (Ne), atomic number 10 — noble gas, period 2. 10 protons, about 10 neutrons in its commonest isotope, and 10 electrons in shells 2, 8 ([He] 2s² 2p⁶). Standard atomic weight 20.18. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Argon atom (Ar) — Argon (Ar), atomic number 18 — noble gas, period 3. 18 protons, about 22 neutrons in its commonest isotope, and 18 electrons in shells 2, 8, 8 ([Ne] 3s² 3p⁶). Standard atomic weight 39.95. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Krypton atom (Kr) — Krypton (Kr), atomic number 36 — noble gas, period 4. 36 protons, about 48 neutrons in its commonest isotope, and 36 electrons in shells 2, 8, 18, 8 ([Ar] 3d¹⁰ 4s² 4p⁶). Standard atomic weight 83.798. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Xenon atom (Xe) — Xenon (Xe), atomic number 54 — noble gas, period 5. 54 protons, about 77 neutrons in its commonest isotope, and 54 electrons in shells 2, 8, 18, 18, 8 ([Kr] 4d¹⁰ 5s² 5p⁶). Standard atomic weight 131.29. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Radon atom (Rn) — Radon (Rn), atomic number 86 — noble gas, period 6. 86 protons, about 136 neutrons in its commonest isotope, and 86 electrons in shells 2, 8, 18, 32, 18, 8 ([Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁶). Standard atomic weight 222. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))

Atoms · Alkali metals 6

Lithium atom (Li) — Lithium (Li), atomic number 3 — alkali metal, period 2. 3 protons, about 4 neutrons in its commonest isotope, and 3 electrons in shells 2, 1 ([He] 2s¹). Standard atomic weight 6.94. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Sodium atom (Na) — Sodium (Na), atomic number 11 — alkali metal, period 3. 11 protons, about 12 neutrons in its commonest isotope, and 11 electrons in shells 2, 8, 1 ([Ne] 3s¹). Standard atomic weight 22.99. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Potassium atom (K) — Potassium (K), atomic number 19 — alkali metal, period 4. 19 protons, about 20 neutrons in its commonest isotope, and 19 electrons in shells 2, 8, 8, 1 ([Ar] 4s¹). Standard atomic weight 39.098. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Rubidium atom (Rb) — Rubidium (Rb), atomic number 37 — alkali metal, period 5. 37 protons, about 48 neutrons in its commonest isotope, and 37 electrons in shells 2, 8, 18, 8, 1 ([Kr] 5s¹). Standard atomic weight 85.468. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Caesium atom (Cs) — Caesium (Cs), atomic number 55 — alkali metal, period 6. 55 protons, about 78 neutrons in its commonest isotope, and 55 electrons in shells 2, 8, 18, 18, 8, 1 ([Xe] 6s¹). Standard atomic weight 132.91. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Francium atom (Fr) — Francium (Fr), atomic number 87 — alkali metal, period 7. 87 protons, about 136 neutrons in its commonest isotope, and 87 electrons in shells 2, 8, 18, 32, 18, 8, 1 ([Rn] 7s¹). Standard atomic weight 223. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))

Atoms · Alkaline-earth metals 6

Beryllium atom (Be) — Beryllium (Be), atomic number 4 — alkaline-earth metal, period 2. 4 protons, about 5 neutrons in its commonest isotope, and 4 electrons in shells 2, 2 ([He] 2s²). Standard atomic weight 9.0122. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Magnesium atom (Mg) — Magnesium (Mg), atomic number 12 — alkaline-earth metal, period 3. 12 protons, about 12 neutrons in its commonest isotope, and 12 electrons in shells 2, 8, 2 ([Ne] 3s²). Standard atomic weight 24.305. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Calcium atom (Ca) — Calcium (Ca), atomic number 20 — alkaline-earth metal, period 4. 20 protons, about 20 neutrons in its commonest isotope, and 20 electrons in shells 2, 8, 8, 2 ([Ar] 4s²). Standard atomic weight 40.078. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Strontium atom (Sr) — Strontium (Sr), atomic number 38 — alkaline-earth metal, period 5. 38 protons, about 50 neutrons in its commonest isotope, and 38 electrons in shells 2, 8, 18, 8, 2 ([Kr] 5s²). Standard atomic weight 87.62. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Barium atom (Ba) — Barium (Ba), atomic number 56 — alkaline-earth metal, period 6. 56 protons, about 81 neutrons in its commonest isotope, and 56 electrons in shells 2, 8, 18, 18, 8, 2 ([Xe] 6s²). Standard atomic weight 137.33. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Radium atom (Ra) — Radium (Ra), atomic number 88 — alkaline-earth metal, period 7. 88 protons, about 138 neutrons in its commonest isotope, and 88 electrons in shells 2, 8, 18, 32, 18, 8, 2 ([Rn] 7s²). Standard atomic weight 226. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))

Atoms · Metalloids 6

Boron atom (B) — Boron (B), atomic number 5 — metalloid, period 2. 5 protons, about 6 neutrons in its commonest isotope, and 5 electrons in shells 2, 3 ([He] 2s² 2p¹). Standard atomic weight 10.81. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Silicon atom (Si) — Silicon (Si), atomic number 14 — metalloid, period 3. 14 protons, about 14 neutrons in its commonest isotope, and 14 electrons in shells 2, 8, 4 ([Ne] 3s² 3p²). Standard atomic weight 28.085. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Germanium atom (Ge) — Germanium (Ge), atomic number 32 — metalloid, period 4. 32 protons, about 41 neutrons in its commonest isotope, and 32 electrons in shells 2, 8, 18, 4 ([Ar] 3d¹⁰ 4s² 4p²). Standard atomic weight 72.63. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Arsenic atom (As) — Arsenic (As), atomic number 33 — metalloid, period 4. 33 protons, about 42 neutrons in its commonest isotope, and 33 electrons in shells 2, 8, 18, 5 ([Ar] 3d¹⁰ 4s² 4p³). Standard atomic weight 74.922. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Antimony atom (Sb) — Antimony (Sb), atomic number 51 — metalloid, period 5. 51 protons, about 71 neutrons in its commonest isotope, and 51 electrons in shells 2, 8, 18, 18, 5 ([Kr] 4d¹⁰ 5s² 5p³). Standard atomic weight 121.76. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Tellurium atom (Te) — Tellurium (Te), atomic number 52 — metalloid, period 5. 52 protons, about 76 neutrons in its commonest isotope, and 52 electrons in shells 2, 8, 18, 18, 6 ([Kr] 4d¹⁰ 5s² 5p⁴). Standard atomic weight 127.6. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))

Atoms · Halogens 5

Fluorine atom (F) — Fluorine (F), atomic number 9 — halogen, period 2. 9 protons, about 10 neutrons in its commonest isotope, and 9 electrons in shells 2, 7 ([He] 2s² 2p⁵). Standard atomic weight 18.998. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Chlorine atom (Cl) — Chlorine (Cl), atomic number 17 — halogen, period 3. 17 protons, about 18 neutrons in its commonest isotope, and 17 electrons in shells 2, 8, 7 ([Ne] 3s² 3p⁵). Standard atomic weight 35.45. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Bromine atom (Br) — Bromine (Br), atomic number 35 — halogen, period 4. 35 protons, about 45 neutrons in its commonest isotope, and 35 electrons in shells 2, 8, 18, 7 ([Ar] 3d¹⁰ 4s² 4p⁵). Standard atomic weight 79.904. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Iodine atom (I) — Iodine (I), atomic number 53 — halogen, period 5. 53 protons, about 74 neutrons in its commonest isotope, and 53 electrons in shells 2, 8, 18, 18, 7 ([Kr] 4d¹⁰ 5s² 5p⁵). Standard atomic weight 126.9. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Astatine atom (At) — Astatine (At), atomic number 85 — halogen, period 6. 85 protons, about 125 neutrons in its commonest isotope, and 85 electrons in shells 2, 8, 18, 32, 18, 7 ([Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵). Standard atomic weight 210. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))

Atoms · Post-transition metals 8

Aluminium atom (Al) — Aluminium (Al), atomic number 13 — post-transition metal, period 3. 13 protons, about 14 neutrons in its commonest isotope, and 13 electrons in shells 2, 8, 3 ([Ne] 3s² 3p¹). Standard atomic weight 26.982. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Gallium atom (Ga) — Gallium (Ga), atomic number 31 — post-transition metal, period 4. 31 protons, about 39 neutrons in its commonest isotope, and 31 electrons in shells 2, 8, 18, 3 ([Ar] 3d¹⁰ 4s² 4p¹). Standard atomic weight 69.723. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Indium atom (In) — Indium (In), atomic number 49 — post-transition metal, period 5. 49 protons, about 66 neutrons in its commonest isotope, and 49 electrons in shells 2, 8, 18, 18, 3 ([Kr] 4d¹⁰ 5s² 5p¹). Standard atomic weight 114.82. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Tin atom (Sn) — Tin (Sn), atomic number 50 — post-transition metal, period 5. 50 protons, about 69 neutrons in its commonest isotope, and 50 electrons in shells 2, 8, 18, 18, 4 ([Kr] 4d¹⁰ 5s² 5p²). Standard atomic weight 118.71. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Thallium atom (Tl) — Thallium (Tl), atomic number 81 — post-transition metal, period 6. 81 protons, about 123 neutrons in its commonest isotope, and 81 electrons in shells 2, 8, 18, 32, 18, 3 ([Xe] 4f¹⁴ 5d¹⁰ 6s² 6p¹). Standard atomic weight 204.38. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Lead atom (Pb) — Lead (Pb), atomic number 82 — post-transition metal, period 6. 82 protons, about 125 neutrons in its commonest isotope, and 82 electrons in shells 2, 8, 18, 32, 18, 4 ([Xe] 4f¹⁴ 5d¹⁰ 6s² 6p²). Standard atomic weight 207.2. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Bismuth atom (Bi) — Bismuth (Bi), atomic number 83 — post-transition metal, period 6. 83 protons, about 126 neutrons in its commonest isotope, and 83 electrons in shells 2, 8, 18, 32, 18, 5 ([Xe] 4f¹⁴ 5d¹⁰ 6s² 6p³). Standard atomic weight 208.98. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))
Polonium atom (Po) — Polonium (Po), atomic number 84 — post-transition metal, period 6. 84 protons, about 125 neutrons in its commonest isotope, and 84 electrons in shells 2, 8, 18, 32, 18, 6 ([Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁴). Standard atomic weight 209. (≈ 0.1–0.5 nm across (the nucleus is ~100,000× smaller than drawn))

Orbitals · Hybrid orbitals 5

sp hybrid orbitals — One s and one p orbital mix into two sp hybrids pointing 180° apart — the bonding in linear molecules such as BeCl₂, CO₂ and acetylene. Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)
sp² hybrid orbitals — One s and two p orbitals give three sp² hybrids at 120° in a plane — trigonal planar carbon in ethylene and benzene. Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)
sp³ hybrid orbitals — One s and three p orbitals give four sp³ hybrids pointing to the corners of a tetrahedron (109.5°) — carbon in methane and diamond. Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)
sp³d hybrid orbitals — Five hybrids toward the corners of a trigonal bipyramid, as in PCl₅ (the classic textbook picture; modern bonding models describe it differently). Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)
sp³d² hybrid orbitals — Six hybrids toward the corners of an octahedron, as in SF₆ (textbook model). Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)

Orbitals · Molecular orbitals 10

σ1s bonding molecular orbital — Two 1s orbitals in phase: electron density builds up between the nuclei and holds them together (H₂). Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)
σ*1s antibonding molecular orbital — Two 1s orbitals out of phase: a node between the nuclei pushes them apart. Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)
σ2p bonding molecular orbital — Two 2p orbitals pointing at each other along the bond overlap end-on into a σ bond (with small back lobes). Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)
σ*2p antibonding molecular orbital — The out-of-phase end-on combination of two 2p orbitals: a node between the nuclei. Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)
π2p bonding molecular orbital — Two parallel 2p orbitals overlap side-on above and below the bond axis — the π bond of a double bond. Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)
π*2p antibonding molecular orbital — Parallel 2p orbitals out of phase: four lobes with a node between the atoms (the LUMO of ethylene). Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)
Benzene π system (lowest π orbital) — The six carbon 2p orbitals of benzene all in phase: two rings of electron density above and below the ring — delocalised aromatic π electrons. Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)
Benzene HOMO (π orbital with one node) — One of benzene’s two degenerate highest occupied π orbitals: one nodal plane through the ring. Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)
Butadiene π orbitals (ψ₁ and ψ₂) — Buta-1,3-diene’s HOMO ψ₂: the four p orbitals combine with one node in the middle of the chain — the basis of conjugation and the Diels–Alder reaction. Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)
Ethylene π bond — The π bond of ethylene: two carbon p orbitals side by side, above and below the C=C axis. Drawn from the hydrogen-like wavefunction; blue and orange are the two phases (signs) of ψ. (≈ 0.1–1 nm)

Crystals · Metal structures 4

Simple cubic packing (polonium) — Atoms only at the corners of a cube, touching along the edges — 52% of space filled, 6 neighbours. Only polonium crystallises this way. (≈ 0.3–0.7 nm unit cell)
Body-centred cubic metal (iron, sodium) — An atom at each corner and one in the centre, touching along the body diagonal — 68% packing, 8 neighbours. α-iron, chromium, tungsten and the alkali metals. (≈ 0.3–0.7 nm unit cell)
Face-centred cubic metal (copper, aluminium) — Atoms at the corners and face centres, touching along the face diagonals — cubic close packing, 74% filled, 12 neighbours. Copper, silver, gold, aluminium, nickel. (≈ 0.3–0.7 nm unit cell)
Hexagonal close-packed metal (magnesium, zinc) — ABAB stacking of close-packed layers — 74% filled, 12 neighbours. Magnesium, zinc, titanium, cobalt. (≈ 0.3–0.7 nm unit cell)

Crystals · Ionic & covalent structures 10

Diamond (and silicon) structure — Every carbon bonded to four others at the corners of a tetrahedron — an FCC lattice with half the tetrahedral holes filled. Silicon and germanium share it. (≈ 0.3–0.7 nm unit cell)
Graphite (layered) — Sheets of hexagonal rings (graphene layers) stacked ABAB 3.35 Å apart and held by weak van der Waals forces — so graphite is soft and conducts along its layers. (≈ 0.3–0.7 nm unit cell)
Rock-salt structure (sodium chloride) — Two interpenetrating FCC lattices: each Na⁺ surrounded by six Cl⁻ and each Cl⁻ by six Na⁺. Also MgO, LiF, AgCl, PbS. (≈ 0.3–0.7 nm unit cell)
Caesium chloride structure — A Cs⁺ in the body centre of a cube of eight Cl⁻ (two interpenetrating simple cubic lattices). Also CsBr, NH₄Cl, β-brass. (≈ 0.3–0.7 nm unit cell)
Zinc blende structure (sphalerite, ZnS) — Zn²⁺ in half the tetrahedral holes of an FCC lattice of S²⁻ — like diamond with two kinds of atom. Also GaAs, CdTe, SiC. (≈ 0.3–0.7 nm unit cell)
Wurtzite structure (ZnS, ZnO, GaN) — The hexagonal form of ZnS: tetrahedral Zn and S on an HCP lattice. Zinc oxide and gallium nitride (blue LEDs) crystallise this way. (≈ 0.3–0.7 nm unit cell)
Fluorite structure (calcium fluoride) — Ca²⁺ on an FCC lattice with F⁻ in all eight tetrahedral holes (8 : 4 coordination). Also UO₂, ZrO₂; the antifluorite Li₂O swaps the ions. (≈ 0.3–0.7 nm unit cell)
Rutile structure (titanium dioxide) — Each Ti⁴⁺ inside an octahedron of six O²⁻, each O²⁻ bonded to three Ti — the commonest form of TiO₂ (white pigment). Also SnO₂, MnO₂. (≈ 0.3–0.7 nm unit cell)
Perovskite structure (CaTiO₃, SrTiO₃) — A large cation (Ca, Sr) at the corners, a small one (Ti) in the centre of an octahedron of six oxygens on the face centres — the structure of solar-cell perovskites and ferroelectrics (BaTiO₃). (≈ 0.3–0.7 nm unit cell)
Ice Ih (hydrogen-bonded lattice) — Ordinary ice: every water molecule hydrogen-bonded to four others in open hexagonal rings — why ice is less dense than water. (≈ 0.3–0.7 nm unit cell)

Crystals · Packing & holes 4

Close packing — ABAB stacking (hexagonal) — Close-packed layers stacked A-B-A-B: the third layer sits directly over the first — hexagonal close packing (hcp).
Close packing — ABC stacking (cubic) — Close-packed layers stacked A-B-C-A-B-C: the third layer covers the holes of the first — cubic close packing (ccp = fcc).
Tetrahedral hole — A small hole between four touching spheres at the corners of a tetrahedron; a sphere 0.225× their radius fits inside.
Octahedral hole — The hole surrounded by six touching spheres at the corners of an octahedron; a sphere 0.414× their radius fits inside (Na⁺ in NaCl).

Crystals · Defects 5

Schottky defect — A missing cation and a missing anion, so the crystal stays neutral — common in highly ionic solids like NaCl and KCl.
Frenkel defect — A small cation has left its site and sits in an interstitial hole nearby — common in AgCl, AgBr and ZnS.
Substitutional impurity — A foreign ion takes the place of a host ion — doping (e.g. Ca²⁺ in NaCl, which also leaves a cation vacancy).
Interstitial impurity — A small foreign atom squeezed into a gap between lattice sites — carbon in iron makes steel.
Edge dislocation — An extra half-plane of atoms pushed into the crystal; the lattice bends around its end. Dislocations moving through metals make them ductile.

Ions · Monatomic anions 10

Fluorine ion (F⁻) — F⁻ — fluoride: an anion that has gained 1 electron. Ionic radius ≈ 1.33 Å (drawn to scale against the other ions).
Chlorine ion (Cl⁻) — Cl⁻ — chloride: an anion that has gained 1 electron. Ionic radius ≈ 1.81 Å (drawn to scale against the other ions).
Bromine ion (Br⁻) — Br⁻ — bromide: an anion that has gained 1 electron. Ionic radius ≈ 1.96 Å (drawn to scale against the other ions).
Iodine ion (I⁻) — I⁻ — iodide: an anion that has gained 1 electron. Ionic radius ≈ 2.2 Å (drawn to scale against the other ions).
Oxygen ion (O²⁻) — O²⁻ — oxide: an anion that has gained 2 electrons. Ionic radius ≈ 1.4 Å (drawn to scale against the other ions).
Sulfur ion (S²⁻) — S²⁻ — sulfide: an anion that has gained 2 electrons. Ionic radius ≈ 1.84 Å (drawn to scale against the other ions).
Nitrogen ion (N³⁻) — N³⁻ — nitride: an anion that has gained 3 electrons. Ionic radius ≈ 1.46 Å (drawn to scale against the other ions).
Selenium ion (Se²⁻) — Se²⁻ — selenide: an anion that has gained 2 electrons. Ionic radius ≈ 1.98 Å (drawn to scale against the other ions).
Hydrogen ion (H⁻) — H⁻ — hydride: an anion that has gained 1 electron. Ionic radius ≈ 1.4 Å (drawn to scale against the other ions).
Phosphorus ion (P³⁻) — P³⁻ — phosphide: an anion that has gained 3 electrons. Ionic radius ≈ 2.12 Å (drawn to scale against the other ions).

Ions · Hydrated ions (in water) 4

Hexaaqua metal ions [M(H₂O)₆]ⁿ⁺ (octahedral) — Six water molecules round a metal ion at the corners of an octahedron, their oxygens turned in. Choose the metal: sodium ion [Na(H₂O)₆]⁺; magnesium ion [Mg(H₂O)₆]²⁺; aluminium ion [Al(H₂O)₆]³⁺; copper(II) ion [Cu(H₂O)₆]²⁺; iron(III) ion [Fe(H₂O)₆]³⁺. Na⁺ in water: six water molecules around it (octahedral), oxygens pointing in. Mg²⁺ holds its six waters very tightly (octahedral) — the shape that binds ATP and DNA. Al³⁺ polarises its waters so strongly that they release H⁺ — solutions of aluminium salts are acidic. The pale-blue ion of copper(II) salts in water: Jahn–Teller distorted, with two longer axial Cu–O bonds. Fe³⁺ in water: octahedral, pale violet, and acidic enough to start hydrolysing to brown iron(III) hydroxide.
Hydrated lithium ion [Li(H₂O)₄]⁺ — Li⁺ held by four water molecules at the corners of a tetrahedron, their oxygens turned towards the small, strongly charged ion. Red = oxygen, white = hydrogen.
Hydrated potassium ion (K⁺ with eight waters) — The larger K⁺ holds about eight, more loosely bound water molecules — why K⁺ passes K⁺ channels that block Na⁺. Red = oxygen, white = hydrogen.
Hydrated chloride ion (Cl⁻ with six waters) — An anion in water: the waters turn a hydrogen towards Cl⁻ instead of their oxygen. Red = oxygen, white = hydrogen.

Natural forms · Gases 6

Hydrogen-filled balloon — Hydrogen is the lightest gas — a balloon of it rises, and pops with a bang when lit. (H₂) (≈ 5–20 cm (a lab sample))
Helium-filled balloon — Helium is lighter than air and does not burn — the gas in party balloons. (He) (≈ 5–20 cm (a lab sample))
Dry ice (solid carbon dioxide) — Solid CO₂ at −78.5 °C turns straight into gas (sublimes); the white fog is condensed water vapour. (CO₂) (≈ 5–20 cm (a lab sample))
Coloured gases in gas jars (Cl₂, NO₂, Br₂, I₂, F₂) — The colours of the coloured gases: yellow-green chlorine, brown nitrogen dioxide, orange bromine vapour, violet iodine vapour and pale yellow fluorine. Show one of them with “Show”. (≈ 5–20 cm each)
Gas discharge tubes (emission colours) — Gases glowing in discharge tubes, each with its own colour (its line spectrum): hydrogen, helium, neon, argon, krypton, xenon, nitrogen, mercury, carbon dioxide and sodium. Show one of them with “Show”. (≈ 5–20 cm each)
Compressed gas cylinders (colour codes) — Gas cylinders whose shoulder colour identifies the gas (European EN 1089-3 code): oxygen white, nitrogen black, CO₂ grey, argon dark green, hydrogen red, acetylene maroon, helium brown, ammonia yellow. Show one of them with “Show”. (≈ 5–20 cm each)

Lab experiments · Separation & purification 6

Fractional distillation — A fractionating column packed with glass beads between the flask and the still head separates liquids with close boiling points (e.g. ethanol from water, crude-oil fractions).
Steam distillation — Steam from a generator flask is blown through plant material, carrying volatile oils (e.g. limonene from orange peel) over into the condenser.
Vacuum (short-path) distillation — Lowering the pressure lowers boiling points, so heat-sensitive liquids distil gently; a "cow" receiver collects several fractions without breaking the vacuum.
Recrystallisation — An impure solid is dissolved in the minimum of hot solvent, filtered hot, then cooled in ice so pure crystals grow while impurities stay dissolved.
Growing a crystal on a thread — A seed crystal hanging on a thread from a pencil grows slowly in a saturated solution (alum or copper sulfate) as the solvent evaporates.
Making a salt (copper sulfate from copper oxide) — Excess black copper(II) oxide is warmed with dilute sulfuric acid, filtered, and the blue filtrate evaporated to crystallise copper(II) sulfate — three stages on the bench.

Lab experiments · Gases & gas tests 7

Collecting a gas over water — Gas from a reaction flask bubbles through a delivery tube into an upturned measuring cylinder full of water in a trough, pushing the water out.
Limewater test for carbon dioxide — Gas from heating a carbonate (or breathing out) bubbles through limewater, which turns milky as calcium carbonate precipitates.
Glowing splint test for oxygen — A glowing wooden splint bursts back into flame in a test tube of oxygen.
Squeaky pop test for hydrogen — A lighted splint at the mouth of a test tube of hydrogen goes out with a squeaky "pop" as hydrogen burns.
Damp litmus test for ammonia and chlorine — Ammonia turns damp red litmus blue; chlorine bleaches damp blue litmus white — two test tubes side by side.
Ammonia fountain — Ammonia is so soluble that a drop of water injected into a flask of the gas sucks water up through a jet — a pink fountain (phenolphthalein in alkali).
Diffusion of ammonia and hydrogen chloride — Cotton wool soaked in ammonia and in hydrochloric acid at the two ends of a glass tube: a white ring of ammonium chloride forms nearer the HCl end, because NH₃ molecules are lighter and diffuse faster.

Lab experiments · Rates, energy & equilibrium 9

Rate of reaction by mass loss — Marble chips and hydrochloric acid in a flask on a balance, with a cotton-wool plug: the mass falls as carbon dioxide escapes.
Disappearing-cross experiment (thiosulfate + acid) — Sodium thiosulfate and hydrochloric acid slowly turn cloudy with sulfur; you time how long until the black cross under the flask can no longer be seen.
Iodine clock reaction — Clear solutions that suddenly turn blue-black after a set time, when the iodine produced finally reacts with starch — faster in the warmer, more concentrated beakers.
Elephant toothpaste — Hydrogen peroxide decomposed by potassium iodide (or yeast) in soapy water erupts as a huge column of oxygen-filled foam.
Enthalpy of neutralisation (cup calorimeter) — Acid and alkali mixed in an insulated polystyrene cup with a thermometer and lid: the temperature rise gives the heat of neutralisation.
Combustion of fuels (spirit burner + copper can) — A spirit burner heats water in a copper calorimeter; the temperature rise and the fuel burnt give the energy released per gram of alcohol.
NO₂ ⇌ N₂O₄ equilibrium (hot and cold) — Two sealed tubes of nitrogen dioxide: in hot water the equilibrium shifts to brown NO₂, in ice to colourless N₂O₄ — Le Chatelier’s principle.
Blue bottle reaction — A flask of alkaline glucose with methylene blue turns blue when shaken (oxygen dissolves) and slowly fades colourless again as glucose reduces the dye.
pH titration with a probe and data logger — A pH probe in a beaker on a magnetic stirrer while a burette adds base; the logger draws the titration curve live.

Electrochemistry · Experiments 6

Electrolysis of brine (U-tube) — Electrolysing sodium chloride solution in a U-tube with carbon electrodes: chlorine (pale green, bleaches litmus) at the anode, hydrogen at the cathode, sodium hydroxide left in solution.
Electrolysis of copper sulfate (copper electrodes) — With copper electrodes, copper dissolves from the anode and plates onto the cathode — the mass lost equals the mass gained (Faraday’s laws).
Electroplating a key with copper — An object made the cathode in copper sulfate solution becomes coated with a thin, even layer of copper from the copper anode.
Lemon battery — Zinc and copper electrodes in lemons, wired in series, light an LED: the lemon juice is the electrolyte, zinc the anode and copper the cathode.
Voltaic pile — Volta’s first battery (1800): a stack of zinc and copper discs separated by brine-soaked cloth.
Concentration cell — Two copper electrodes in copper sulfate solutions of different concentration joined by a salt bridge still give a small voltage — the Nernst equation in action.

Inorganic · Bases & hydroxides 10

Potassium hydroxide / Lithium hydroxide / Caesium hydroxide and 1 more — An inorganic base or hydroxide. These compounds draw alike, so they share one item — choose the compound in the settings: Potassium hydroxide (HKO, 56.11 g/mol); Lithium hydroxide (HLiO, 24 g/mol); Caesium hydroxide (CsHO, 149.91 g/mol); Rubidium hydroxide (HORb, 102.47 g/mol). Structures from PubChem (2D drawings).
Calcium hydroxide / Magnesium hydroxide / Barium hydroxide and 2 more — An inorganic base or hydroxide. These compounds draw alike, so they share one item — choose the compound in the settings: Calcium hydroxide (CaH2O2, 74.09 g/mol); Magnesium hydroxide (H2MgO2, 58.32 g/mol); Barium hydroxide (BaH2O2, 171.34 g/mol); Strontium hydroxide (H2O2Sr, 121.63 g/mol); Beryllium hydroxide (BeH2O2, 43.03 g/mol). Structures from PubChem (2D drawings).
Copper(II) hydroxide / Zinc hydroxide / Nickel(II) hydroxide and 4 more — An inorganic base or hydroxide. These compounds draw alike, so they share one item — choose the compound in the settings: Copper(II) hydroxide (CuH2O2, 97.56 g/mol); Zinc hydroxide (H2O2Zn, 99.4 g/mol); Nickel(II) hydroxide (H2NiO2, 92.71 g/mol); Cobalt(II) hydroxide (CoH2O2, 92.95 g/mol); Manganese(II) hydroxide (H2MnO2, 88.95 g/mol); Iron(II) hydroxide (FeH2O2, 89.86 g/mol); Cadmium hydroxide (CdH2O2, 146.43 g/mol). Structures from PubChem (2D drawings).
Sodium amide / Lithium amide — An inorganic base or hydroxide. These compounds draw alike, so they share one item — choose the compound in the settings: Sodium amide (H2NNa, 39.01 g/mol); Lithium amide (H2LiN, 23 g/mol). Structures from PubChem (2D drawings).
Potassium hydride / Lithium hydride — An inorganic base or hydroxide. These compounds draw alike, so they share one item — choose the compound in the settings: Potassium hydride (HK, 40.11 g/mol); Lithium hydride (HLi, 8 g/mol). Structures from PubChem (2D drawings).
Tetrabutylammonium hydroxide — An inorganic base or hydroxide. C16H37NO, 259.47 g/mol (IUPAC: tetrabutylazanium hydroxide). Structure (PubChem has no 3D model, so its 2D drawing is shown) from PubChem.
Tetramethylammonium hydroxide — An inorganic base or hydroxide. C4H13NO, 91.15 g/mol (IUPAC: tetramethylazanium hydroxide). Structure (PubChem has no 3D model, so its 2D drawing is shown) from PubChem.
Calcium hydride — An inorganic base or hydroxide. CaH2, 42.09 g/mol. Structure (PubChem has no 3D model, so its 2D drawing is shown) from PubChem.
Chromium(III) hydroxide — An inorganic base or hydroxide. CrH6O3, 106.04 g/mol (IUPAC: chromium;trihydrate). Structure (PubChem has no 3D model, so its 2D drawing is shown) from PubChem.
Lanthanum hydroxide — An inorganic base or hydroxide. H3LaO3, 189.93 g/mol (IUPAC: lanthanum(3+) trihydroxide). Structure (PubChem has no 3D model, so its 2D drawing is shown) from PubChem.

Organic · Carboxylic acids 11

Cinnamic acid — A carboxylic acid (–COOH). C9H8O2, 148.16 g/mol (IUPAC: (E)-3-phenylprop-2-enoic acid). Real 3D structure from PubChem.
Maleic acid — A carboxylic acid (–COOH). C4H4O4, 116.07 g/mol (IUPAC: (Z)-but-2-enedioic acid). Real 3D structure from PubChem.
Chloroacetic acid — A carboxylic acid (–COOH). C2H3ClO2, 94.5 g/mol (IUPAC: 2-chloroacetic acid). Real 3D structure from PubChem.
Sorbic acid — A carboxylic acid (–COOH). C6H8O2, 112.13 g/mol (IUPAC: (2E,4E)-hexa-2,4-dienoic acid). Real 3D structure from PubChem.
2-chlorobenzoic acid — A carboxylic acid (–COOH). C7H5ClO2, 156.56 g/mol. Real 3D structure from PubChem.
1-adamantanecarboxylic acid — A carboxylic acid (–COOH). C11H16O2, 180.24 g/mol (IUPAC: adamantane-1-carboxylic acid). Real 3D structure from PubChem.
2-naphthoic acid — A carboxylic acid (–COOH). C11H8O2, 172.18 g/mol (IUPAC: naphthalene-2-carboxylic acid). Real 3D structure from PubChem.
Propiolic acid — A carboxylic acid (–COOH). C3H2O2, 70.05 g/mol (IUPAC: prop-2-ynoic acid). Real 3D structure from PubChem.
Mellitic acid — A carboxylic acid (–COOH). C12H6O12, 342.17 g/mol (IUPAC: benzene-1,2,3,4,5,6-hexacarboxylic acid). Real 3D structure from PubChem.
Squaric acid — A carboxylic acid (–COOH). C4H2O4, 114.06 g/mol (IUPAC: 3,4-dihydroxycyclobut-3-ene-1,2-dione). Real 3D structure from PubChem.
Meldrum's acid — A carboxylic acid (–COOH). C6H8O4, 144.12 g/mol (IUPAC: 2,2-dimethyl-1,3-dioxane-4,6-dione). Real 3D structure from PubChem.

Biochemistry · Teaching set (amino acids, cofactors, sugars) 5

Pyrrolysine — A biomolecule from the biochemistry teaching set. C12H21N3O3, 255.31 g/mol (IUPAC: 2-amino-6-[(3-methyl-3,4-dihydro-2H-pyrrole-2-carbonyl)amino]hexanoic acid). Real 3D structure from PubChem.
Carnitine — A biomolecule from the biochemistry teaching set. C7H15NO3, 161.2 g/mol (IUPAC: 3-hydroxy-4-(trimethylazaniumyl)butanoate). Real 3D structure from PubChem.
NADPH — A biomolecule from the biochemistry teaching set. C21H30N7O17P3, 745.4 g/mol. Real 3D structure from PubChem.
Plastoquinone — A biomolecule from the biochemistry teaching set. C53H80O2, 749.2 g/mol. Structure (PubChem has no 3D model, so its 2D drawing is shown) from PubChem.
2-deoxy-D-ribose — A biomolecule from the biochemistry teaching set. C5H10O4, 134.13 g/mol (IUPAC: (3S,4R)-3,4,5-trihydroxypentanal). Real 3D structure from PubChem.