Patterns & properties · About 8 min
Periodic trends
Learn periodic trends with a clear comparison chart, worked examples and practice questions. See why the patterns happen and where exceptions matter.
Learn chemistry,
made clearer.
Work through core chemistry one concept at a time—with step-by-step derivations, interactive calculators, 3D molecular geometry, and self-checking practice questions.
- Guided modules
- 7 lessons
- Interactive tools
- Calculators & 3D
- Classroom ready
- A4 & Letter PDFs
Chemistry lessons & interactive calculators
Seven structured guides for secondary-school and introductory college chemistry. Follow them in sequence or jump straight to the calculation or concept you need.
Interactive calculators & 3D tools
Molar mass calculatorSubatomic particle counter3D molecular polarity stageAtoms & bonding · About 7 min
Valence electrons & ions
Find valence electrons using group numbers, work out common ion charges, and practice writing formulas. Includes a chart, examples and explained answers.
Atomic structure · About 6 min
Interactive counterProtons, neutrons & electrons
Calculate protons, neutrons and electrons for atoms and ions using atomic number, isotope mass number and charge, with worked examples and practice.
Orbitals & electrons · About 9 min
Electron configuration
Practice electron configurations, orbital diagrams, noble-gas notation and ions. Work through oxygen, chromium and iron with explained answers.
Molecular structure · About 10 min
3D molecule stageLewis structures & polarity
Learn to draw Lewis structures, find molecular shapes and decide whether a molecule is polar. Compare water, carbon dioxide and methane in 3D.
Chemical calculations · About 8 min
Molar mass calculatorMolar mass
Calculate molar mass and percent composition with step-by-step examples. Count atoms in formulas, handle parentheses and hydrates, and check your answers.
The periodic table · About 7 min
Element families
Learn periodic table families, including alkali metals, halogens and noble gases. Compare group properties, common ions and important exceptions.
Printable chemistry worksheets & reference sheets
Print a clean periodic table, a one-page reference sheet, or a topic worksheet formatted for A4 and US Letter. Toggle the teacher’s answer key on or off before printing.
See why every answer works
Each lesson explains the underlying physical model, walks through worked examples step by step, and gives the reasoning behind every practice question. Use the interactive calculators and 3D molecular stage when a structure is easier to understand by testing it yourself.
Source links take you directly to OpenStax, IUPAC, and CIAAW for the definitions and standard atomic weights behind the lessons. Where a classroom diagram or rounded value simplifies the chemistry, the lesson states the boundary clearly.
Read about our scientific sources