Mercury helide (not halide). Extremely unstable synthetic compound that rapidly and readily releases its helium.
Helium is an inert gas, of which there are no known compounds. However, it is also a gas, and do to the free random movement of all gasses, and heliums relatively high average velocity as predicted by the kinetic theory of matter because of its low mass, helium molecules in a gas are moving quite rapidly. Helium will mix with all gasses, to some extend, but will mix the most at high temperatures, with gasses of similar molecular weights, in small areas.
hydrogen and helium are the special elements because the electron in the outer most shell of the hydrogen is 1 but it is not a metal it is a non metal whereas in helium the electron in the outer most shell are 2 but it is not a metal there fore it is a noble gas.
Helium is considered an inert noble gas. Only some unstable compunds of helium are known today: HeNe, HgHe10, WHe2.
Helium is an inert gas, of which there are no known compounds. However, it is also a gas, and do to the free random movement of all gasses, and heliums relatively high average velocity as predicted by the kinetic theory of matter because of its low mass, helium molecules in a gas are moving quite rapidly. Helium will mix with all gasses, to some extend, but will mix the most at high temperatures, with gasses of similar molecular weights, in small areas.
hydrogen and helium are the special elements because the electron in the outer most shell of the hydrogen is 1 but it is not a metal it is a non metal whereas in helium the electron in the outer most shell are 2 but it is not a metal there fore it is a noble gas.