They are the details of the Revised Taxonomy and I will be held on

1. Summary of Flame Testing and
Bohr’s Quantum Model of the Atom

2. Who?
• Niels Bohr
• Copenhagen, Denmark
• October 7, 1885-
November 18, 1962
• Occupation: Professor of
Theoretical Physics at
Copenhagen University
• Won the Nobel Prize for his
Atomic Model (Planetary
Model of the Atom)

3. What Did He Do in 1913?
• Proposed that electrons
in atoms exist in orbits
at discrete distances
from the nucleus
• The orbits represent
specific energies and
are called energy
levels (2-d) or energy
shells (3-d).
• This model shows that
energy in matter is
quantized or can only
be absorbed and
released in specific
small amounts. The
exact amounts of
energy absorbed and
released are specific to
each type of atom.

4. Continued…
• When an atom absorbs certain specific frequencies or energies of
electromagnetic radiation, the electrons obtain a higher-energy orbit
farther from the nucleus (the excited state). Each type of atom can
only absorbs certain frequencies and energies of radiation.
• Eventually, The electrons return back to a lower-energy orbit (the
ground state) and release the energy as photons of
electromagnetic radiation. Each photon carries a specific amount or
quantum of energy. The released photons are seen as spectral
lines in an atomic emission spectrum!

5. Picture of Bohr Model
E = E higher-energy orbit – E lower-energy orbit = E photon = h

6. Why do we see a discontinuous
emission spectrum?
• Each type of atom can only absorb and release
certain frequencies and energies of electromagnetic
radiation related to the exact energy differences
between the energy levels in that specific atom.
• If matter (and atoms) could absorb and release any
and all possible amounts of electromagnetic
radiation energy, we ought to always get a
continuous emission spectrum, but we never do.

7. Other types of photons are also released
by atoms….producing other spectral lines
but they are invisible to the naked eye!

8. Importance and Limitations
• Bohr’s atomic model explains
the atomic emission spectra
of hydrogen the best.
• Bohr’s atomic model is the
first quantum model of the
atom. It explains how energy
and matter interact at the
atomic level and describes
how atoms can only absorb
and release certain energies.
• Bohr’s model implies that
electrons orbit the nucleus in
circular orbits like planet orbit
a sun (but really they do not).
• Bohr’s model does not
accurately explain the
chemical properties of
elements.

9. Application of Spectroscopy in
Geology
X-ray map of Calcium in a garnet
crystal in a garnet schist.