One hundred fifty years after Russian chemist Dmitri Mendeleev published his system for neatly arranging the elements, the periodic table it gave birth to hangs in every chemistry classroom in the ...

Note: This video is designed to help the teacher better understand the lesson and is NOT intended to be shown to students. It includes observations and conclusions that students are meant to make on ...

The periodic table has become an icon of science. Its rows and columns provide a tidy way of showcasing the elements — the ingredients that make up the universe. It seems obvious today, but it wasn’t ...