Lab 5 – Emission SpectraLab 5 – Emission Spectra

Light WavesLight Waves

Wavelength (Wavelength ())

Red LightRed Light – – Longer Wavelength, Lower Energy

Blue LightBlue Light – – Shorter Wavelength, Higher Energy

ColorColor Wavelength Wavelength

Formation of Emission and Dark Line Spectra

Formation of Emission and Dark Line Spectra

Kirchhoff’s Laws

1.1. A hot, dense glowing object (a solid or A hot, dense glowing object (a solid or dense gas) emits a dense gas) emits a continuouscontinuous spectrum. spectrum.

2.2. A hot, low-density gas emits light of only A hot, low-density gas emits light of only certain wavelengths—a certain wavelengths—a bright linebright line spectrum. spectrum.

3.3. When light having a continuous spectrum When light having a continuous spectrum passes through a cool gas, passes through a cool gas, dark linesdark lines appear in appear in the continuous spectrum.the continuous spectrum.

+P+P

22

33

44

656 nm

7000 Å7000 Å4000 Å4000 Å

-e-e

Hydrogen Hydrogen AtomAtom

11

-e-e

-e-e

55

-e-e

486 nm

434 nm

-e-e410 nm

-e-e

How to Excite an AtomHow to Excite an Atom

+P+P

11

22

33

44

-e-e

6563 Å6563 Å

1. Absorption of a 1. Absorption of a PhotonPhoton

7000 Å7000 Å4000 Å4000 Å

Hydrogen Hydrogen AtomAtom

White Light Source

Aluminum

Oxygen

Argon

Calcium

Carbon

Helium

Hydrogen

Iron

Krypton

Magnesium

Neon

Nitrogen

Sulfur

Sodium

Xenon

The EndThe End