Mendeleev’s Table

Patterns before explanations

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Mendeleev (1869) arranged elements so that properties repeat periodically.
• He left gaps and correctly predicted elements like gallium and germanium.
• The true order is by atomic number (Moseley, 1913).

Steps

1. A bold arrangement
2. The prediction
3. Predicting germanium
4. Moseley’s X-rays
5. Moseley’s law
6. Out of order