Transcript II. Bohr Model of the Atom

Ch. 4 - Electrons in Atoms
II. Bohr Model of the Atom
(p. 94 - 97)
Excited and Ground State
Ground state: lowest energy state of
an atom
Excited state: an atom has a higher
potential energy than it had in its
ground state
When an excited atom returns to its
ground state, it gives off the energy it
gained as EM radiation
A. Line-Emission Spectrum
excited state
ENERGY IN
PHOTON OUT
ground state
B. Bohr Model
 2) e- exist only in orbits with specific
amounts of energy called energy levels
 When e- are in these orbitals, they
have fixed energy
 Energy of e- are higher when they are
further from the nucleus
B. Bohr Model
Therefore…Bohr model leads
us to conclude that:
e- can only gain or lose
certain amounts of energy
only certain photons are
produced
B. Bohr Model
65
4
3
2
1
Energy of photon
depends on the
difference in energy
levels
Bohr’s calculated
energies matched
the IR, visible, and
UV lines for the H
atom
Each element has a unique bright-line
emission spectrum.
“Atomic Fingerprint”
Helium
Bohr’s calculations only worked for
hydrogen! 