Like most elements on the periodic table, selenium is an element that no one ever looks at in A level. Of course everyone knows the standard carbon, nitrogen, oxygen, sometimes if we’re lucky we’ll get a chromium or even a krypton!
like everything else on the periodic table, you can work out what an element is like by where it is placed- just as silicon is like carbon (as seen earlier), so selenium is like sulfur as they are both in column 6, so have the same number of electrons in their outer shell and so react in the same way. When we think of sulfur we think of sulfuric acid and the very smelly H2S that makes us gag and shrink inside our lab coats when doing practicals. Selenium also makes Hydrogen selenide in the same way which is equally as smelly but not one to do practicals with as it is even more acidic than the nasty H2S.
Se is an interesting element which is “photo conductive” meanings it can conduct electricity better when under bright light. this makes it good for “semiconductors” or light meters however Selenium’s ability to turn light energy to electrical energy means it is often used in solar cells. Apart from that I wouldn’t say that Se is used for anything spectacular in life- the usual paints and pigments as well as being used to color glass.
Selenium was discovered by a Swedish chemist J. Berzelius and is named after the Greek word for moon “selene”. A pretty name for perhaps what he thought was a pretty element- Se can form red black and gray allotropes 🙂 however i think that he named it “selenium” because of its solid silvery gray allotrope that to a 19th century chemist does look very “moon-like”/