The chemical element of atomic number 2, an inert gas that is the lightest member of the noble gas series.
- ‘There he worked with Born on atomic theory, writing a joint paper with him on helium.’
- ‘During the history of our universe, more helium was made because the process that drives the stars turns hydrogen into helium.’
- ‘In composition it resembles a small star, with helium and hydrogen as the main gases.’
- ‘Over the next few years many types of laser were built, some using a mixture of helium and neon, others carbon dioxide or organic dyes.’
- ‘Eventually, there will not be any hydrogen left in the center of the Sun to make helium.’
- ‘They were the ones who were always crying and throwing fits when they lost their helium balloons.’
- ‘However, if a proton is added to the hydrogen atom, a new element, helium is created.’
- ‘During the last years of his life he worked steadily on the wave mechanics of the hydrogen and helium atom.’
- ‘Cool the detectors with liquid nitrogen instead of solid hydrogen or liquid helium.’
- ‘Ramsay realized that argon and helium might be members of a hitherto unsuspected new group in the Periodic Table.’
- ‘Argon is denser than air, and certainly helium, which means that it has more molecules to retain heat.’
- ‘Because it is chemically inert, helium was not identified on Earth until some time later, in 1895.’
- ‘When most of the hydrogen is fused into helium, fusion stops and and gravity again takes over.’
- ‘Other light elements that are commonly proposed for the outer core are silicon, carbon, helium, and nitrogen.’
- ‘The atomic elements heavier than hydrogen and helium could not have been produced during the inferno of the Big Bang.’
- ‘Even though helium is twice as dense as hydrogen, this is less than one metric ton of gas.’
- ‘Today, balloons in Japan are lifted by hot air rather than the more expensive helium or hydrogen.’
- ‘At launch, the balloon is partially inflated with helium and expands as it rises.’
- ‘In practice air is nowadays never used in deep diving, the nitrogen being replaced by helium, which is far less soluble in fat.’
- ‘Does it contain yet more unknown chemical elements, like helium?’
Late 19th century: modern Latin, from Greek hēlios sun because its existence was inferred from an emission line in the sun's spectrum.
We take a look at several popular, though confusing, punctuation marks.