Representation of Helium
|Helium atomic number
|Helium atomic mass
||Sir William Ramsay in London, Per Teodor Cleve and Nils Abraham Langlet.
What is Helium?
- Helium is the element which you can find on the upper right side of the periodic table with atomic number 2. It comes first amongst the family of the noble gases.
- It holds one atomic orbital and was named by Lockyer and Frankland. Its name is derived from the Greek word “Helios” meaning Sun. Scientists knew there is an enormous amount of helium in the Sun before it was discovered.
- Helium falls under inert gas since its outermost electron orbital is full with two electrons. Helium can also be found in lasers, compressed air tanks and coolant in nuclear reactors.
- It holds the lowest boiling and melting points among the all other elements. The Nuclear fusion of hydrogen in stars generates a significant amount of helium.
Helium has two known stable isotopes – 3He and 4He. The abundance of helium-3 and helium-4 corresponds to 0.0002% and 99.9998% respectively. This difference in abundances can be observed in the Earth’s atmosphere, where the ratio of 4He atoms to 3He atoms is approximately 1000000:1.
Physical Properties of Helium
||0.95 K (or -272.2oC)
||4.222 K (or -268.928oC)
||0.1786 g/L at STP; 0.145 g.cm-3 at its melting point
|Critical Temperature and Pressure
||5.195 K; 0.227 MPa
||2.177 K; 5.043 kPa
|Appearance (at STP)
Chemical Properties of Helium
|First Ionization Energy
||2372.3 kilojoules per mole
|Second Ionization Energy
||5250.5 kilojoules per mole
|Van der Waals Radius
|Enthalpy of Fusion
Uses of Helium
- The primary use of Helium goes in altitudes research and meteorological balloons.
- It is utilized as an inert protective gas in autogenous welding.
- It is the only cooler capable of declining temperature lower than 15K (-434ºF).
- Helium is also used in the production of germanium crystals and silicon crystals.
- Since it has the ability to diffuse through solids much faster than air, helium is used industrially for pipeline leak detection.
- This element is also used in gas chromatography as a carrier gas.
- Owing to its low melting point, liquid helium has numerous applications in cryogenics, magnetic resonance imaging (MRI), and superconducting magnets.