+1 = 5 

ㄆㄧㄝpiē

  1. 非金屬元素符號1H,同位素質量1,普通99.8%

protium 1H, light hydrogen, the most common isotope of hydrogen, having no neutron, so atomic weight 1
protium
Protium (ein Wasserstoffisotop, H)​ (S, Chem)​