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 (thorium and …
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-272.3℃，沸点 …
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 liquid at …
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 原子序数 2 发现人 威廉· …
Helium 浏览器：隐私优先、轻量高效的开源 Chromium 桌面浏览器
2 days ago · Helium 浏览器是一款基于 Chromium 的开源桌面浏览器项目，旨在提供极简、私密与高效的网页浏览体验。 它由开源组织 imputnet 开发，全部源码和构建工具均托管在 GitHub 仓库 上，采 …
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.
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 exploration, …
Helium - Wikiwand
Helium is a chemical element; it has symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert, monatomic gas and the first in the noble gas ...
Helium – expert written, user friendly element information
Helium was made in the first three minutes of the universe’s existence, when temperatures everywhere were high enough for nuclear fusion to occur. This short, high energy phase is represented at the …