We assess the impact of the trace element ^ { 22 } \mathrm { Ne } on the cooling and seismology of a liquid C/O white dwarf ( WD ) .
Due to this elements ’ neutron excess , it sinks towards the interior as the liquid WD cools .
The gravitational energy released slows the WD ’ s cooling by 0.5-1.6 Gyr .
In addition , the ^ { 22 } \mathrm { Ne } abundance gradient changes the periods of the high radial order g -modes at the 1 % level .