# What is the difference between the Rydberg constants #R_H = "109678.77 cm"^(-1)# and #R_(oo) = "109737.32 cm"^(-1)#?

##### 1 Answer

It just depends on what kinds of atoms you use it for.

These **Rydberg constants** are (*Inorganic Chemistry, Miessler et al.*):

#color(blue)(R_(oo)) = 1.0973731568539_(55)xx10^7# #"m"^(-1)#

#= color(blue)(109737.31568539_(55))# #color(blue)("cm"^(-1))#

#color(blue)(R_(H)) = 1.0967877174307_(10)xx10^7# #"m"^(-1)#

#= color(blue)(109678.77174307_(10))# #color(blue)("cm"^(-1))# where subscript digits indicate digits of high uncertainty.

**"infinite" nuclear mass**, is used for heavy atoms, which have a heavy nucleus, considered to be "infinitely" heavier than the mass of each electron.

**proton nuclear mass**, is used for hydrogen atom only, because its nucleus is only one proton, which is about