Calendar

Leap year checker

366
1
12
365

A leap year has 366 days. Century years are leap years only when divisible by 400.

A useful way to begin

A concrete example

Why this matters

The periodic table, built for exploration

118 elements. One clear map of matter. Explore the periodic table, open any element, or jump straight into scientific converters.

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.

Phenomena

Everyday scientific phenomena explained with living diagrams and concise, carefully checked text. The motion helps show the mechanism; the article explains what the diagram simplifies.

Evaporation is the passage of molecules from the surface of a liquid into the gas phase. Water does not need to boil for this to happen.