Caesium
The team at Periodic Videos has created a TED-Ed Lesson for every element of the periodic table. Here are five grams of caesium in water... but did you know caesium is also used to define the length of a second?
The team at Periodic Videos has created a TED-Ed Lesson for every element of the periodic table. Here are five grams of caesium in water... but did you know caesium is also used to define the length of a second?