Electromagnetic Spectrum and Bohr Model of the Atom

Rutherford Atom Model

Electrons orbit nucleus like planets around the sun.

Emission Spectra of Atoms

Observing light emitted by heated gases under low pressure.

Electromagnetic Spectrum

Continuum of all electromagnetic waves by frequency and wavelength.

Frequency

Number of waves passing through a point in 1 sec.

Wave Theory

Electromagnetic energy moves as sinusoidal waves.

Particle Theory

Atoms absorb energy in limited quanta, E = hν.

Photoelectric Effect

Light shining on metal surface emits electrons.

Planck's Constant

h = 6.626 x 10^-34 J.s in E = hν.

Kirchhoff's Three Laws of Spectroscopy

• hot solid = continuous spectrum of light

• hot gas = light w/ spectral lines at discrete wavelengths

• hot solid/cool gas = almost continuous spectrum we/ gaps at wavelengths

Flame Tests and Atomic Spectra

Elements emit characteristic spectra.

Rydberg Equation

Mathematical model for spectral lines.

Bohr Model

Electrons move in quantized energy levels around the nucleus.

Excited States

Electrons jump to higher orbits by absorbing energy.

Photon Emission

Electrons emit energy in the form of light.

Ground State

Lowest energy level in which electrons reside.

highest energy (highest frequency)

gamma rays

lowest energy

radio waves

as wavelength increases (wave theory)

frequency decreases to keep c constant

As frequency increases (particle theory)

wavelength decreases, energy increases

constant

3 × 10^8

Rydberyg constant

1.097 × 10^7

plancks constant

6.626 × 10^-34