Selenium - Periodic Table of Videos
The team at periodicvideos has created a TED-Ed Lesson for every element of the periodic table. This one is about selenium -- element number 34 and you can find it below sulfur on the periodic table.
Selenium was discovered in 1817 by Jöns Jacob Berzelius. Due to its similarity to tellurium, which was named after the Earth, Berzelius named the new element after the moon.