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From Longman Dictionary of Contemporary English
Related topics: Chemistry
heliumhe‧li‧um /ˈhiːliəm/ noun [uncountable]  HCa gas that is lighter than air and is used to make balloons float. It is a chemical element: symbol He
Examples from the Corpus
heliumUranium has two radioactive isotopes, each of which decays to an isotope of lead and helium.Typically, the fuels are isotopes of the three lightest elements, hydrogen, helium, and lithium.The Kamikaze: One part liquid helium, two parts prussic acid.These solar gases contain a large amount of helium, the second most abundant element in the Sun.The job is made more difficult now because of self-sealing materials and the use of helium.But in addition there remained the puzzle of how the helium came to be in the springs.However, the story can be simplified without losing its essence by neglecting the helium for the time being.The two orbiting electrons of the helium atom form a shell.
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