Their is 2 valence electrons
The group on the periodic table that would have 0 electronegativity due to the fact that their valence shell is full, i.e, have a full octet would be the inert or noble gases. They have a total of 8 electrons in their valence shell and are thus inert and cannot strongly attract electrons toward itself, from neighbouring atom electrons as it does not need to.
Hydrogen is the only atom that does not have neutron electrons in the first energy level/shell.
The answer is: 2 NH3 —> N2 + 3 H2
