SciShow: ChemistryHank talks about a shiny element that has fascinated humans for millenia; and everyone's favorite squeaky-voice gas and why it's important for more than party balloons.

Why our love affair with the rare earth elements has a dark side; and the awesomeness of the periodic table and the genius of the man who invented it.

A sweet-tasting substance we humans just love - where it comes from, why we need it and how we could maybe stand to love it a little less.

Hank delves into the details about that very popular substance: caffeine; the story of his favorite genius lady scientist and radioactive superhero, Marie Curie; and the high fructose corn syrup - the new "dark lord of nutrition" - to help explain the ambiguities around all the claims being made about it.

Hank explains the science behind the effects of that wackiest of weeds, cannabis sativa - aka marijuana; and the man behind the periodic table - the brilliant Russian chemist Dmitri Mendeleev.

Other SciShows: Infusion and Dose. Other Crash Courses: Biology and World History.

Watch the full documentary now (playlist - 47 minutes)