Helium [He] – Element Details, Facts, Properties, Trends, Uses, Comparison with other elements
Helium is element 2 in periodic table with atomic number 2, atomic weight 4.002602, symbol ‘He’, Helium has a Face Centered Cubic structure and Colorless. It is a noble gas element. Trivial name of Helium is noble gases*, aerogens.
History of Helium
The element Helium was discovered by Pierre Janssen in the year 1895 in Sweden and United Kingdom . Helium derived its name from the Greek word helios, meaning ‘sun’.
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.
How to Locate Helium on Periodic Table
Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of electrons. The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and ends at bottom right (atomic number 118). Therefore you can directly look for atomic number 2 to find Helium on periodic table.
Another way to read periodic table and locate an element is by using group number (column) and period number (row). To locate Helium on periodic table look for cross section of group 18 and period 1 in the modern periodic table.
Helium Atomic and Orbital Properties
Helium atoms have 1 electrons and the electronic shell structure is  with Atomic Term Symbol (Quantum Numbers) 2S1/2.
Atomic Structure of Helium
Ground State Electronic Configuration of Helium – neutral Helium atom
The ground state electronic configuration of Neutral Helium atom is 1s2. The portion of Helium configuration that is equivalent to the noble gas of the preceding period, is abbreviated as 1s2]. For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used.This is important as it is the Valence electrons 1s2, electrons in the outermost shell that determine the chemical properties of the element.
Unabbreviated electronic configuration of neutral Helium
Complete ground state electronic configuration for the Helium atom, Unabbreviated electronic configuration