...: Balloons - Amazon FREE DELIVERY possible on eligible purchasesHarmful effects: Helium is not known to be toxic. Characteristics: Helium is a light large airtight bag filled with hot air or a lighter-than-air gas after hydrogen. Helium constitutes the 23% of all elemental matter measured by mass. Helium is formed in The Earth by natural radioactive decay of heavier elements. Most of this helium migrates to the surface and enters the atmosphere.Helium atoms have 2 electrons and the shell structure is 2. The ground state electronic configuration of neutral helium is 1s 2 and the term symbol of helium is 1 S 0.. Helium: description Your user agent does not support the HTML5 Audio element.Helium is the second lightest and second most common element in the universe.It is at the top of the noble gas group in the periodic table. Characteristics and Properties At room temperature helium is an odorless
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