Helium, He is a gas at room temperature and is colourless, tasteless, odorless and is not poisonous.

    Atomic Number - 2

    Weight of a Helium atom - 4.002602g/molˉ1（Weight per Helium atom）

    Melting point is- ?272.20 °C

    Boiling point is- ?268.93 °C

    This means that Helium can exist as a liquid but the temperature is would have to reach would be near absolute zero which is at the moment physically impossible.

    Even though Helium is relatively rare on Earth it is the second most abundant element in the Universe（as we know it）, because of nuclear fusion of hydrogen in stars more helium is being produced. On Earth helium is mainly found by the radioactive decay of radioactive elements. Helium is given off as α alpha radiation as ionised Helium particles.

    Helium was first discovered by a French astronomer on the 18th of August 1868 during a total solar eclipse when a bright yellow line 587.49 nanometers was discovered.

    Alpha particles were shown that they are helium nuclei by scientist Ernest Rutherford in1907.

    The main use of helium was mainly to replace the use of hydrogen gas in zeppelins as hydrogen was extremely flammable. The use that many people know of however is for pumping up party balloons, but some other uses are to use for welding （the helium used for this must be extremely pure） and helium can be mixed with hydrogen and used as a laser.

    Helium is found in stars and is reacted through Nuclear Fusion to make the other elements found throughout the Universe.

    氦，He 在室温下是一种气体，无色，尝不出也闻不到，无毒。

    原子序数-2

    氦原子的质量-4.002602克/摩尔（每个氦原子的质量）

    （译者注：4是氦的相对原子量，氦原子的质量约是6.6969*10^-27 kg）

    融解温度- -272.20°C

    沸腾温度- ?268.93 °C

    就是说，氦只有在接近绝对零度的时候才以液态存在，而绝对零度目前是无法达到的。

    （译者注：绝对零度无法达到，但接近是可以达到的。）

    尽管氦在地球上比较稀有，它在宇宙中却是第二号最丰富的元素（就我们所知）,原因是恒星中氢的核聚变会形成氦。在地球上，氦主要发现在放射性元素的放射性衰变中。阿尔法衰变会产生一个离子化的氦离子，就这样得到了氦。

    （译者注：地球上氦虽然少，也是自然广泛存在的，可以工业提纯制造的。）

    氦最初由法国天文学家在1868年8月18日发现，在一次日全食中，发现了587.49纳米的亮黄线。

    1907年，科学家Ernest Rutherford（阿内斯特 罗斯福）,证实阿尔法衰变的粒子是氦的原子核。

    氦的主要用途是替代氢，用在气球中，因为氢太容易燃烧了。很多人知道的用途是给集会气球充气，其它的用途是用于焊接（这种用途的氦气必须要非常纯）,氦可以和氢混合用于激光。

    恒星中都有氦，氦参与原子核聚变反应，形成整个宇宙中所有的其它元素。