'''Háídrójìn''' tabi '''Hydrogen''' ({{pron-en|ˈhaɪdrɵdʒɨn}},<ref>
{{cite book
|last= Simpson|first=J.A.
Ìlà 11:
|year=1989
|isbn=0-19-861219-2
}}</ref> {{respell|HYE|dro-jin}}) is theje [[chemical element|apilese kemika]] withpelu [[atomic number|nomba atomu]] 1. ItO isje representedsisoju byfun thelatowo [[chemical symbol|symbolami-idamo]] '''H'''. With anPelu [[atomic weight|iwuwo atomu]] ofiye {{val|1.00794|u=[[atomic mass unit|u]]}} ({{val|1.007825|u=[[atomic mass unit|u]]}} for [[Hydrogen-1]]), hydrogen is the lightest and [[abundance of the chemical elements|most abundant]] chemical element, constituting roughly 75 % of the Universe's elemental mass.<ref>
