Helium - Wikipedia
On Earth, it is relatively rare—5.2 ppm by volume in the atmosphere. Most terrestrial helium present today is created by the natural radioactive decay of heavy radioactive elements …
Helium | Definition, Properties, Uses, & Facts | Britannica
Dec 4, 2025 · Helium, chemical element, inert gas of Group 18 (noble gases) of the periodic table. The second lightest element, helium is a colorless, odorless, and tasteless gas that becomes …
氦气_百度百科
氦气（Helium），稀有气体元素的一种，化学元素符号为He，原子序数2，原子量4.0026，是一种无色、无臭、无味、不可燃的单原子惰性气体，非金属元素，密度为0.1786kg/m3，熔点 …
About Helium - Bureau of Land Management
Helium is an odorless, nontoxic, colorless, tasteless gas; it has a very low chemical reactivity and it is lighter than air. These characteristics are why helium plays a prominent role in space …
Helium - Own the Air
Helium replaces cell towers with small devices called Hotspots that provide affordable connectivity and expand coverage wherever people gather, work, and move. Businesses and individuals …
Helium - Element information, properties and uses | Periodic Table
Element Helium (He), Group 18, Atomic Number 2, s-block, Mass 4.003. Sources, facts, uses, scarcity (SRI), podcasts, alchemical symbols, videos and images.
Helium | He (Element) - PubChem
Helium is an inert gas and does not easily combine with other elements. There are no known compounds that contain helium, although attempts are being made to produce helium …
氦 - 维基百科，自由的百科全书
At the origin of the helium leak detection method was the Manhattan Project and the unprecedented leak-tightness requirements needed by the uranium enrichment plants.
氦（化学元素）_百度百科
外文名 Helium CAS登录号 7440-59-7 EINECS登录号 231-168-5 熔 点 -272.2 ℃ [16] 沸 点 -268.93 ℃ [16] 密 度 0.1785 kg/m³ [16]（0℃） 外 观 无色气体 溶解性 不溶于水、乙醇 原子序 …
氦 - 維基百科，自由的百科全書
At the origin of the helium leak detection method was the Manhattan Project and the unprecedented leak-tightness requirements needed by the uranium enrichment plants.