Rydberg formula
Atomic models · Physics
Bohr atom
Interactive 3DElectrons orbit the nucleus in shells — switch element to see H, He and Li fill their shells.
Controls
Drag the sliders or type a value — the simulation updates live.
Study notes
(a) Use the Rydberg formula to find the wavelength of the n = 5 → 2 transition in hydrogen. (b) Find the corresponding line for He⁺ (Z = 2). Solution: (a) 1/λ = R(1/2² − 1/5²) = 1.097×10⁷ × (0.25 − 0.04) = 1.097×10⁷ × 0.21 = 2.304×10⁶ m⁻¹. λ = 1/(2.304×10⁶) = 4.34×10⁻⁷ m = 434 nm — H-gamma ✓. (b) 1/λ = RZ²(1/4 − 1/25) = 4 × 2.304×10⁶ = 9.216×10⁶ m⁻¹ → λ = 108.5 nm — the same jump in He⁺ lies deep in the UV, at exactly 1/4 the wavelength.