chemistry

Browse all 118 chemical elements →

• Atomic Mass & Isotopes Calculator

  See why atomic mass is a decimal: it is the abundance-weighted average of an element's isotopes. Slide the isotope mix for chlorine, boron, or copper and watch the average.

• Balancing Chemical Equations

  Set the coefficients on a real reaction and watch a live atom tally check both sides. Learn why every element must balance (conservation of mass) with steppers and a 'Show me' answer.

• Bond & Molecular Polarity

  Compare two atoms to see δ+/δ−, the dipole arrow, ΔEN, and bond type, then check whether a whole molecule is polar or cancels by symmetry.

• Electron Configuration Builder

  Pick any element from hydrogen to krypton and watch its ground-state electron configuration and Bohr shell diagram build up in Aufbau order, including the chromium and copper exceptions.

• Interactive Bohr Model: Atomic Shell Diagram Builder

  Build the Bohr model of any element (Z 1-118). Pick an atomic number to see the nucleus and electron shells fill, with electrons-per-shell and outer-shell count.

• Interactive Periodic Table

  Explore all 118 elements in an interactive periodic table: recolor by category, state, or block, and open any element for its electron configuration, Bohr model, and uses.

• Interactive pH Scale

  Slide across the 0–14 pH scale to see each value's acidity classification, its hydrogen-ion concentration [H⁺] = 10⁻ᵖᴴ, and a familiar everyday substance at that pH.

• Ionic vs Covalent Bonds (and Metallic)

  Pick two elements and compare their electronegativity. The ΔEN difference predicts an ionic, covalent (polar or nonpolar), or metallic bond.

• Lewis Dot Structures

  Draw the Lewis dot structure of common molecules. See bonds as lines, lone pairs as dots, count valence electrons, and meet the octet-rule exceptions.

• Mole Ratios & Stoichiometry

  Use a balanced equation as a recipe: coefficients give the mole ratio, molar mass converts grams to moles, and one ratio hop takes you from any substance to another.

• Molecular Geometry (VSEPR)

  Pick a molecule and watch VSEPR predict its 3D shape. See how lone pairs and bonding regions set the geometry, bond angle, and hybridization.

• Molecule Builder: Build Molecules Atom by Atom

  A free build-a-molecule game: tap atoms into the tray, bond them, and watch real molecules snap together. Take on challenges or free-build to discover all 14.

• Noble Gases (Group 18) Explorer

  Explore the noble gases of group 18 (helium, neon, argon, krypton, xenon, radon, and oganesson) and see why a full outer shell makes them so unreactive.

• Periodic Table Game: Find the Element

  A free, fast periodic table game: we name an element, you race to click it on the table. Beat your best time, learn where every element lives, no signup.

• Periodic Trends Heat-Map

  Color the periodic table by electronegativity, ionization energy, or electron affinity. See how each trend moves across periods and down groups.

• States of Matter: The Heating Curve, Phase Changes, and Latent Heat

  Add heat to ice and watch it melt then boil on a live heating curve: the temperature plateaus at 0 and 100 °C while energy breaks bonds. Covers the states, phase changes, and latent heat.

• The Gas Laws: Boyle's, Charles's, Gay-Lussac's, Avogadro's, and the Ideal Gas Law

  Pick a gas law and the held-constant quantities lock; drag the one free control and watch pressure, volume, and temperature respond, with every formula, graph, and worked example in real units.

• The Mole & Molar Mass

  Pick a substance to see its molar mass built up element by element, then convert freely between moles, grams, and particles with Avogadro's number.

• The Particle Box: Kinetic Molecular Theory

  Heat, squeeze, and cool a live box of atoms to watch pressure, the speed distribution, and even melting and boiling emerge from the collisions. Kinetic theory you can play with.

• Types of Chemical Reactions

  Classify reactions as synthesis, decomposition, single replacement, double replacement, or combustion, then use each pattern to predict the products.

• Valence Electrons & Lewis Dot Symbols

  Pick a main-group element and see its Lewis electron-dot symbol. Learn the group rule that gives valence electrons for groups 1, 2, and 13 to 18.