He
Helium · element 2
Noble Gas · Gas at room temperature
Helium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table. Its boiling and melting points are the lowest among all the elements.
Key facts
Atomic mass
4.0026022 u
how heavy one atom is
Phase (room temp.)
Gas
Density
0.1786 g/L
how tightly packed it is
Melting point
0.95 K (-272 °C)
when solid turns to liquid
Boiling point
4.222 K (-269 °C)
when liquid turns to gas
Period
1
its row in the periodic table
Group
18
its column in the periodic table
Block
S-block
the neighbourhood it lives in
Electron configuration
1s2
where its electrons live
Shells
2
electrons in each layer, inside to out
Discovered by
Pierre Janssen
who found it
Appearance
colorless gas, exhibiting a red-orange glow when placed in a high-voltage electric field
what it looks like
Source: Wikipedia