The mass of an electron is ¹/₁₈₃₅ that of the hydrogen atom.
The diameter of an electron is estimated to be about 3 × 10⁻¹³ cm.
The diameter of the atomic nucleus is of the order of magnitude 10⁻¹³ to 10⁻¹² cm.
The diameter of a hydrogen atom in the normal state (the diameter of the first stationary orbit in Bohr’s model) is 1·056 × 10⁻⁸ cm.
The Balmer constant K = 3·29 × 10¹⁵.
The Planck constant h = 6·54 × 10⁻²⁷.
An energy quantum is E = hν.
The Balmer-Ritz formula for the frequencies of the lines in the hydrogen spectrum is
| ν = K |  | 1 | - | 1 |  |
| n″ ² | n′ ² |
DIAGRAMS OF SPECTRA