The hydrogen atom

Energy is measured in eV, or electron volts

Light (photon) is electromagnetic energy

Since only permitted electron orbits (energies), there are only permitted photon energies that interact with the atom.

The photon energy equals the energy difference of the electron orbits

(not shown)

(true colors)

Energy = 12.8 – 10.2 = 2.6 eV

n=1

n=3

n=2

Energy Increasing

Lyman

Balmer

Paschen

Balmer Series

Blackbody Radiation

max = 3,000,000

T nanometer

Etotal = constant x T 4 J/s/m2

Etotal = area under BB curve

T = absolute temperature

Absolute temperature measures the internal kinetic energy of an object. This is the energy from all the motions of the atoms.

Absolute Temperature

Units = Kelvins

Measures kinetic energy (motion and/or speed) of particles in a gas, solid, or a liquid

Shown below is a gas …

coolerhotter

Stars have absorption spectra.

Stellar spectrum showing hydrogen absorption.

Ionization is the removal of an electron from an atom by a very high energy photon

Electron is “kicked” off the atom by a photon with E > 13.6 eV(in this case- for hydrogen atom)

The resulting atom is called an ion and it has totally new electron orbits/energies.Thus, the spectral lines are completely different.

E = Energy

BB just right.BB too hot. hydrogen ionized.

BB too cool.

BB = blackbody (spectrum).

ionized atoms (ions)

excited atoms

ground-state atoms

Different atoms have different temperature dependencies because energy needed to ionize them is different.

Finally, to get temperature… use many ions. At any given temperature, some atoms are in ground state, some excited (creating absorption lines), and some ionized (creating absorption different lines from same element).

Spectral Class or TypeHistorically by Key Absorption Features

Now Understood as a Temperature Sequence

O, B, A, F, G, K, Mcoolerhotter

The Doppler Shift (light).

BLUE SHIFTHigher frequencyHigher energyShorter wavelength

RED SHIFTLower frequency

Lower energyLonger wavelength

The Doppler Shift (sound).

Higher pitch Lower pitch

REDSHIF

BLUESHIF

MID TERM EXAM 1

WEDNESDAY FEBRUARY 6 HERE @ USUAL TIME

All LECTURED MATERIAL AND READING ASSIGNMENTSBUT NOT

GRAVTITY AND KEPLERS LAWS