Hydrogen Spectral Series Explained

Understanding electron transitions and energy levels WALT: Analyse hydrogen emission spectra and identify different spectral series Year 13 Physics - NCEA Level 3

Learning Objectives & Success Criteria

WALT: Explain how electron transitions create spectral lines Success Criteria: You can identify the five hydrogen spectral series Success Criteria: You can calculate wavelengths using the Rydberg equation Success Criteria: You can explain the relationship between energy levels and photon emission Differentiation: Visual learners - spectral diagrams, Kinesthetic learners - hands-on activities

Hydrogen Atom Structure Review

Single proton nucleus with one electron Electron occupies discrete energy levels (n = 1, 2, 3...) Ground state: n = 1 (lowest energy) Excited states: n > 1 (higher energy) Energy levels become closer together at higher n values

Think-Pair-Share

What happens when an electron falls from a higher energy level to a lower one? Discuss with your partner for 2 minutes Be ready to share your ideas with the class

Lyman Series - UV Region

Electron transitions TO n = 1 (ground state) From n = 2, 3, 4, 5... → n = 1 Produces ultraviolet radiation (UV) Lyman α (n=2→1): 121.6 nm Discovered by Theodore Lyman (1906) Important in stellar spectroscopy

Balmer Series - Visible Light

Electron transitions TO n = 2 From n = 3, 4, 5, 6... → n = 2 Produces visible light (400-700 nm) Hα (n=3→2): 656.3 nm (red) Hβ (n=4→2): 486.1 nm (blue-green) First series discovered (1885) - visible to naked eye

Calculate Balmer Wavelengths

Use Rydberg equation: 1/λ = R(1/n₁² - 1/n₂²) R = 1.097 × 10⁷ m⁻¹ (Rydberg constant) Calculate λ for n=4→2 transition Work in pairs - check your answer with neighbors Extension: Calculate the energy of this photon

Infrared Series Comparison

{"left":"Paschen Series (n→3): Near-infrared, 820-1875 nm, Discovered 1908\nBrackett Series (n→4): Mid-infrared, 1458-4050 nm, Discovered 1922\nPfund Series (n→5): Far-infrared, 2278-7400 nm, Discovered 1924","right":"All invisible to human eye\nDetected using special IR instruments\nImportant for atmospheric studies"}

Complete Hydrogen Spectrum Overview

Applications & Summary

Astronomy: Identifying hydrogen in stars and galaxies Medical: MRI imaging uses hydrogen nuclei Environmental: Atmospheric composition analysis Key Pattern: Higher final n → longer wavelengths All series follow the same Rydberg equation Success Check: Can you name all five series and their regions?