+2 = 6 

ㄉㄠdāo

  1. 同位素原子核含有中子質子原子核一個中子質量原子核重氫」。

deuterium 2H, heavy hydrogen, isotope of hydrogen having 1 neutron in its nucleus, so atomic weight 2
deutérium
Deuterium (ein Wasserstoffisotop, D)​ (S, Chem)​