Why do gases like helium escape from Earth's atmosphere?

Answer 1

They're very light in mass. They will tend to rise to high altitudes and for a given temperature, since they are light, they will travel at speeds often fast enough for them escape into space.

Answer 2

Due to its light mass, helium tends to evaporate from the top of the earth's atmosphere, and is lost into interplanetary space.



Reference:

Properties of helium:

1. After hydrogen, helium is the second lightest element.
Density ------ 0.1786 g/L (0 °C, 101.325 kPa)

2. Least reactive of the nearly inert noble gas elements.

3. Its boiling and melting points are the lowest among the elements; except in extreme conditions, it exists only as a gas. (At temperatures near absolute zero and standard pressure, helium exists as a superfluid, a nearly frictionless phase of matter with unusual properties.)

Answer 3

They are so light ,they go to the very top of the atmosphere where the sun heats which accelerates the molecules to escape velocity.

Answer 4

these gases have very less atomic wt. and hece are very light thus can defy the gravity of the earth and escapes from the atmosphere.