★ Must-know
📐 Formula — For a hydrogenic species, an electron can occupy energy states given by , where is the principal quantum number.
📌 Atoms absorb or emit light only at defined wavelengths because only defined amounts of energy are exchanged, producing line spectra.
Further detail
Bohr explains hydrogenic quantization, whereas a complete model is needed for general atoms.
1. What energy does an electron have in the second principal energy level of a hydrogenic species?
2. Why do atoms produce line spectra rather than spectra containing every possible wavelength?
3. An electron moves non-relativistically with its speed doubled while its mass remains constant; how does its de Broglie wavelength change?
What formula gives the energy states of an electron in hydrogenic species?
Why do atoms emit or absorb light only at defined wavelengths?
Because only defined amounts of energy are exchanged, producing line spectra.
What formula did Louis de Broglie propose for a particle's wavelength?
What did the Davisson–Germer experiment prove about electrons?
Electrons exhibit wave behavior by producing a diffraction pattern.
Energy levels in hydrogenic atoms (quantization)
E = -13.6 eV / n² shows quantized energy states.
Matter wave wavelength (de Broglie)
λ = h / p, relates momentum and wavelength.
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