Download Arrangement of Electrons in Atoms

The Development of a New Atomic
Model - 4.1
Problem with Rutherford model –
no explanation of where e-s are
 New info about light led to new
model of the atom
 Before 1900 scientists thought light
traveled like a wave.
 We know now that light behaves
like a wave and like a particle
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Called the dual wave-particle nature of
light!
Electromagnetic Radiation - form of E
that exhibits wavelike behavior as it
travels thru space
Electromagnetic Spectrum - all of the
forms of electromagnetic radiation
(visible light, x-rays, uv and infrared
light, micro and radio waves)
All types of emag rad. move at
3.00 x 108 m/s in a vacuum.
(slightly slower thru matter)
 This is the speed of light
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Wavelength - λ the distance between
corresponding points on adjacent
waves
Frequency - ν the number of waves that
pass agiven point in a specific time, usually
1 second
Frequency is expressed in Hertz (Hz)
c = λν
 The speed of light = wavelength
times frequency
 The wavelength of red light is 7.6 x
10-7 m, calculate the frequency.
 F = speed
= 2.998 x 108 m/s
wavelength
7.6 x 10-7 m
 Frequency = 3.9 x 1014Hz

The emission
of e-s from a
metal when
light shines on
the metal
 Light had to be
a certain freq.
to emit e-s

 Planck
proposed idea of quanta
(E packets)
 Quantum of energy - the
minimum quantitiy of E that can
be lost or gained by an atom
E = hν
 Where E is the energy in joules
of a quantum of radiation
 υ is the frequency in s-1
 h is Planck's constant of 6.626 x
10-34 J * s

Ein. supported Planck by
proposing the duality of light as
particle and wave
 Ein. proposed particles of light
carry a quantum of E called
photons (0 mass)

The E of a photon depends on
the υ of rad.
 E absorbed in whole # of
photons
 Different metals need diff. υ to
remove an e
Electric
current
passed
thru a gas
at a low
pressure
LES = the result
from a narrow
beam of the
emitted light that
is shined through
a prism when it
separated into
colors of the
visible spectrum
The Continuous
Spectrum
Ground state - the lowest E level
of an atom (very stable level)
 Excited state - a state in which an
atom has a higher potential E
than it has in its ground state

When an e- falls from the excited
state, a photon is given off - the E
of the photon is = to the E
difference
 H only emits certain freq. so eexists in specific E levels
