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Practice & Assess

Atomic Spectra

Observe emission and absorption spectra of atoms

Key Concept (HKDSE)

When an electron jumps between energy levels in an atom:
Absorption: photon energy is absorbed to move the electron to a higher level.
Emission: a photon is emitted when the electron falls to a lower level.

Emission Light

No emission yet

Absorption Light

No absorption yet

Controls

Excite Electron To:

Auto-decay from excited states

Series

Lyman (n→1, UV)

None

Balmer (n→2, Visible)

None

Paschen (n→3, IR)

None

Theory

When an electron transitions from a higher energy level (

E_{2}

) to a lower one (

E_{1}

), it emits a photon.

Δ E = E_{2} - E_{1} = h f = \frac{h c}{λ}

Hydrogen Energy Levels:

E_{n} = - \frac{13.6 eV}{n ^{2}}

Energy Levels (eV)

-13.60 eV

0.00

Emission Spectrum

UV RegionVisible LightIR Region

380nm450500550600650750nm

Absorption Spectrum

UV RegionVisible LightIR Region

380nm450500550600650750nm

Controls

Excite Electron To:

Auto-decay from excited states

Series

Lyman (n→1, UV)

None

Balmer (n→2, Visible)

None

Paschen (n→3, IR)

None

Theory

When an electron transitions from a higher energy level (

E_{2}

) to a lower one (

E_{1}

), it emits a photon.

Δ E = E_{2} - E_{1} = h f = \frac{h c}{λ}

Hydrogen Energy Levels:

E_{n} = - \frac{13.6 eV}{n ^{2}}