Arrangement of Electrons in
Atoms
The Development of a New Atomic
Model
The Development of a New Atomic Model
Objectives:
1. Identify the major regions of the electromagnetic
spectrum.
2. Explain the mathematical relationship between
wavelength, frequency and energy of light.
3. Distinguish between a continuous spectrum and line
spectrum.
4. Explain how atoms emit light energy.
Rutherford Model of the Atom
The Wave Description of Light
The Wave Description of Light
Wavelength (λ) – the distance between corresponding
points on adjacent waves
Frequency ()-the number of waves that pass a given
point in a specific time (waves/sec or Hz)
Amplitude- the height of a wave measured from baseline
to peak or baseline to trough.
Speed (c)- distance  time; 3.0 x 108 m/s for light
traveling in a vacuum. (slightly slower through
matter)
The Wave Description of Light
c  
•Wavelength and frequency are inversely
proportional
The Development of a New Atomic Model
Objectives:
1. Explain how line spectra demonstrate the
quantized nature of light energy.
2. Describe the Bohr Model of the Hydrogen
atom.
The Photoelectric Effect
• the emission of electrons from a metal when light shines
on the metal
• The light must have a minimum frequency depending
upon the metal
The Photoelectric Effect
Max Planck (1900) – suggested that objects emit energy
is specific amounts called quanta
Quantum- minimum amount of energy that can be lost
or gained by an atom
E  h
E = energy in Joules
h = Planck’s constant (6.626 x 10-34 J*s)
 = frequency of radiation emitted
The Photoelectric Effect
Albert Einstein (1905) – proposed that light could exist
as a stream of particles with each particle containing a
quantum of energy
photon- particle of electromagnetic energy carrying a
quantum of energy
E  h
The Hydrogen Atom Line Emission Spectrum
• When substances absorb energy, they give of
that energy in the form of electromagnetic
radiation.
ground state – lowest energy state of an atom
excited state – a state with higher potential
energy
Bohr Model of the Hydrogen Atom
Niels Bohr (1913) – proposed a model for the H atom to
account for the hydrogen line spectrum.
Bohr Model of the Hydrogen Atom