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Helium: Difference between revisions
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{{Wikipedia|Helium}} | {{Wikipedia|Helium}} | ||
'''Helium''', symbolised as '''He''', is a colourless, odourless, tasteless, non-toxic, inert monatomic chemical element that heads the noble gas series in the periodic table and whose atomic number is 2. Its boiling and melting points are the lowest among the elements and it exists only as a gas except in extreme conditions. Extreme conditions are also needed to create the small handful of helium compounds, which are all unstable at standard temperature and pressure. In its most common form, helium-4, it has two neutrons in its nucleus, while a second, rarer, stable isotope called helium-3 contains just one neutron. | '''Helium''', symbolised as '''He''', is a colourless, odourless, tasteless, non-toxic, inert monatomic chemical element that heads the noble gas series in the periodic table and whose atomic number is 2. Its boiling and melting points are the lowest among the elements and it exists only as a gas except in extreme conditions. Extreme conditions are also needed to create the small handful of helium compounds, which are all unstable at standard temperature and pressure. In its most common form, helium-4, it has two neutrons in its nucleus, while a second, rarer, stable isotope called helium-3 contains just one neutron. | ||