Oxygen, Radium andSodium

Oxygen
It was thought that water was an element itself the 18th century. The one to disprove this in 1777 was Antonie Lavoisier who named one of the elements oxygen; meaning genorator of acid. His work put oxygen as the leader for combustion, instead of fire. In the 19th century oxygen gas was introduced to the public and popularized by oxygen therepy. At this point oxygen was used to"cure" a variety of illnesses and was said to produce feelings of comfortable heat. It relieved breathing difficulties for as long as the gas lasted.
Radium 
Marie Curie discovered radium in 1898 with the help of her husband Pierre Curie, who dropped his own research to help her. Radium is 300 times more radioactive then uranium and more radioactive then polonium. Radium's main use was for the treatment of cancers because from the beginning it had been known to have the ability to damage skin. Though it was soon exploited for treatment of blood, bone and nerve ailments. Radium was popularized by cartoons and as a cure all. The name radium was added to almost everything; cigars, butter, toothpaste, condoms, beer, jelly and many more. After the 1960's the radium hype ended and is now only used in radiological clinics.
Sodium
With a 589 nanometer wavelength sodium light washes over everything turning the surroundings monochrome. This light that we are so used to actually decieves our eyes, so nothing is the color it seems. The sodium streetlights became common after WWII and immediately gained negative attention from writers. The poet John Betjeman even went so far to call it "yellow vomit thrown out by the new concrete gallows overhead". In every city on every continent the night is turned yellow by sodium lights. Sodium is the most abundant alkali metal on Earth making it a good option for light because its yellow light washes out every other color.