What is the half life of potassium argon dating
The complete octet (eight electrons) in the outer atomic shell makes argon stable and resistant to bonding with other elements.
Its triple point temperature of 83.8058 K is a defining fixed point in the International Temperature Scale of 1990.
A faint line from argon shows in the spectrum of the doomed star Eta Carinae.
Eta Carinae has a mass of more than 100 Earth suns. The first hint of its existence came from English scientist Sir Henry Cavendish as far back as 1785.
In 1892 English physicist John William Strutt (better known as Lord Rayleigh) announced that no matter how it was prepared, oxygen was always 15.882 times denser than hydrogen.
This very precise work had taken ten years to complete.
It is more than twice as abundant as water vapor (which averages about 4000 ppmv, but varies greatly), 23 times as abundant as carbon dioxide (400 ppmv), and more than 500 times as abundant as neon (18 ppmv).
In the universe, argon-36 is by far the most common argon isotope, being the preferred argon isotope produced by stellar nucleosynthesis in supernovas.
The name "argon" is derived from the Greek word meaning "lazy" or "inactive", as a reference to the fact that the element undergoes almost no chemical reactions.
We now know that the ‘something else’, argon, is very unreactive; this enabled Cavendish to find it, but it also prevented him finding out more about it.
(The giant advances in spectroscopy made by Gustav Kirchhoff and Robert Bunsen lay 85 years in the future.) In hindsight, we can say Cavendish slightly underestimated the part of air that isn’t oxygen, nitrogen, or carbon dioxide. After his experiment, more than 100 years passed until scientists again began to think that something about air didn’t quite add up.