why do we add energy? shouldn’t the gas glow all by itself without any help?

Part 3(e): Atomic Physics

Bohr Model of the Atom

Important point:

* Each atom has a unique set of orbits* Each atom produces a unique set of wavelengths when it produces em waves

Part 3(e): Atomic Physics

Bohr Model of the Atom

Important point:

* Each atom has a unique set of orbits* Each atom produces a unique set of wavelengths when it produces em waves* The spectrum of the element can be usedas a “fingerprint” to identify the element

Part 3(e): Atomic Physics

Emmission Spectra for Various Atoms

Part 3(e): Atomic Physics

Bohr Model of the Atom

The Energy Minimun Principle

* The electrons in orbit will existed in theorbit with the lowest possible energy state.

Part 3(e): Atomic Physics

Bohr Model of the Atom

The Exclusion Principle

* No two electrons in an atom will have thesame energy.

Part 3(e): Atomic Physics

Bohr Model of the Atom

Implication

* For atoms with more than one electron, theelectrons will “stack” with the firstelectron in the lowest possible energy state,the second in the second lowest, etc.

Part 3(e): Atomic Physics

Bohr Model of the Atom

Why do we add energy? Shouldn’t the gas glow all by itself without any help?

Yes, but the electrons will populate the lowest energy state. In order to see the spectra to the fullest, energy is used to populate excited states and let the electrons cascade down through the orbits, producing as many characteristic photons as possible.

http://jersey.uoregon.edu/elements/Elements.html

Periodic Table with Spectra

Part 3(e): Atomic Physics

Absorption Spectrum

Part 3(e): Atomic Physics

Absorption Spectrum

Gas

Part 3(e): Atomic Physics

Absorption Spectrum

http://jersey.uoregon.edu/elements/Elements.html

Periodic Table with Spectra

Periodic Table with Spectra

What would an absorption spectrum look like to a computer?

Periodic Table with Spectra

What would an absorption spectrum look like to a computer?

An exercise for the reader

Part 3(e): Atomic Physics

Incandescence

Part 3(e): Atomic Physics

Incandescence

ContinuousSpectrum

Part 3(e): Atomic Physics

Spectral Properties of Incandescence

Energy

Wavelength

Part 3(e): Atomic Physics

Spectral Properties of IncandescenceEnergy

WavelengthBlue Red

Low Temp

High Temp

Part 3(e): Atomic Physics

Spectral Properties of IncandescenceEnergy

WavelengthBlue Red

Low Temp

High Temp

Part 3(e): Atomic Physics

Spectral Properties of IncandescenceEnergy

WavelengthBlue Red

Low Temp

High Temp

Click here to view a temperature adjustable continuous spectrum