Nobel-ity, Part 1
How do chemists design stable compounds?
I can show how noble gases remain stable.
• How do you design a molecule?
• Why are some molecules stable, and not others?
• How would you make a molecule that was useful?
Nobel-ity
• What do you think this molecule does?
• Why is it stable?
Stable molecules
• Redraw the hydrogen spectra
• How many lines?
• What color is each?
Question 1, p. 176
• A. How do you know that the Rutherford model of atom
structure did not explain line spectra?
• Hint: did the Rutherford model have different energy levels
for electrons?
Question 2, p. 177
• B. How do you know that each line is associated with a
different amount of energy?
• Does each color have a different energy?
• Think about wavelengths.
• http://highered.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?it=swf::800::600::/sites/
dl/free/0072482621/59229/Bohr_Nav.swf::The%20Bohr%2
0Atom
• http://player.discoveryeducation.com/index.cfm?guidAssetI
d=244FD84B-CF9C-45F1-9113-23CC31234874
Question 2, p. 177
• C. Why do you think that rapidly moving electrons, not
rapidly moving protons, are responsible for spectral
lines?
• Which one is easier to move?
• Which one is “fatter”?
Question 2, p. 177
• D. How were differences in the amount of dark spaces
between lines important?
• What does it have to do with energy?
Question 2, p. 177
• Read the reading!
• Words:
• Quantum (Quanta)
• Orbit
Question 4, p. 177
Niels Bohr
(Born in Denmark 1885-1962)

Student of Rutherford
Niels Bohr’s Model (1913)
 Electrons
orbit
the nucleus in
circular paths of
fixed energy
(energy levels).
Max Plank
E=hn
E=energy
n=frequency
h=Plank’s constant 6.7x10-34Js
Energy of Emitted Photon
Energy of the emitted photon =
Difference in energy between two states
Energy emitted by the electron as it leaps
from the higher to the lower energy level is
proportional to the frequency of the light
wave.
 Frequency define the color of visible light.

Bohr Atom

http://higheredbcs.wiley.com/legacy/colleg
e/halliday/0471320005/simulations6e/inde
x.htm?newwindow=true
Niels Bohr’s Atom Cont’d
 Electrons
can jump from energy level
to energy level.
 Electrons
absorb or emit light energy
when they jump from one energy level
to another.
Quantum
A
quantum of energy is the amount
of energy required to move an
electron from one energy level to
another.
The energy levels are like the rungs
of a ladder but are not equally
spaced.
Photons

Photons are bundles of light energy that
is emitted by electrons as they go from
higher energy levels to lower levels.
Excited State and Ground State

Ground state: the lowest possible energy
level an electron be at.

Excited state: an energy level higher than
the ground state.
Emission Spectrum

Light emitted produces a unique
emission spectrum.
Hydrogen Emission Spectrum
Violet
Blue
Red
Balmer
Series
Bohr Model for Hydrogen
 The
Bohr model explained the
emission spectrum of the hydrogen
atom but did not always explain those
of other elements.
• Use the stuff I taught you and the stuff in the book to help
your responses
• A: Why did Rutherford’s model of atoms not explain
spectra? Make a labeled sketch with highlight comments
and a caption
• B. Complete the table (figure 4.11)
• Use statements from the reading
• Do AT LEAST all that, plus more if needed
Question 5
• Examine chemical symbols in the book. They explain 2
important aspects of the Bohr model
• A. Which expression shows an ABSORBTION of energy?
• B. Which shows an EMISSION of energy?
• C. Which particle transports energy away from the excited
state of Sr when it falls to the ground state?
• D. Based on flame
Question 6
• D. Based on flame tests, what is a reasonable hypothesis
about the color of an emitted photon from strontium?
• E. Did the heat of the flame ionize the Sr+2 ion? How do
you know?
Question 6