Positronium is just like a H-atom with the proton replaced by the positively charged anti-particle of the electron (called the positron which is as massive as the electron). What would be the ground state energy of positronium ?

Explanation

The total energy of the electron in the stationary states of the hydrogen atom is given by
`E_(n) = - (me^(4))/(8n^(2)epsi_(0)^(2)h^(2))`
where signs are as usual and the m that occurs in the Bohr formula is the reduced mass of electron and proton. Also, the total energy of the electron in the ground state of the hydrogen atom is `-13.6 eV`. For H-atom reduced mass `m_(e)` . Whereas for positronium, the reduced mass is
`m = (m_(e))/(2)`
Hence, the total energy of the electron in the ground state of the positronium atom is
`(-13.6eV)/(2) = - 6.8 eV`.