118 elements. One clear map of matter. Explore the periodic table, open any element, or jump straight into scientific converters.
Nonmetal · Gas
Dmitri Mendeleev arranged the known elements so that recurring chemical properties became visible. He deliberately left gaps where the pattern suggested undiscovered elements should exist. That idea — structure before completeness — still makes the periodic table one of science’s most powerful maps.
Mendeleev also includes fast, focused conversion pages for the quantities used most often in physics, chemistry and everyday science.
Start with something familiar, then follow the elements hidden inside it.
Phone, coffee, tap water, bicycle: ordinary objects are a surprisingly good way to enter chemistry.
Follow an object part by part and discover which elements make its screen, battery, chips and connections possible.
Why do noble gases barely react? Why are alkali metals so lively? Families turn the table into a map of behavior.
Temperature, pressure, energy, mass and more — practical tools with explanations, examples and reference values.
Understanding matter starts with the elements. The periodic table is more than a classification chart: it is a map that reveals families, repeating behaviour and links between substances we encounter every day. The copper in a cable, silicon in a chip, carbon in a pencil and oxygen in the air all belong to the same story. Mendeleev.com is designed to explore that story without turning science into a catalogue of numbers — with element profiles, concrete explanations, converters and, over time, pathways connecting chemistry with objects, technology, energy, life and the environment.