Transcript Chem 167 SI - Iowa State University

Sunday, September 30 at 4:10pm
Some stuff you might have forgotten (already)
Some practice

A mercury atom is initially in its lowest possible
(or ground state) energy level. The atom absorbs
a photon with a wavelength of 185nm, and then
emits a photon with a frequency of 6.88x1014 Hz.
At the end of this series of transitions, the atom
will still be in an energy level above ground
state.

Q: Draw an energy level diagram for this
process, and find the energy of this resulting
excited state, assuming we assign E = 0 to the
ground state.
Photoelectric Practice

What is the kinetic energy of an electron
removed from iron using light with a
wavelength of 101 nm? The binding
energy of an electron in iron is 7.5x10–19 J.

Bonus: what is the speed of this electron?
A brief look at
Bohr’s major contribution was the suggestion
of stable orbits that electrons occupy. His
model is the most common depiction of atoms,
but sadly is also incorrect.
Now to the real show!
What the heck are these things?
The principle quantum number indicates
the shell
 The second indexes energy differences
between orbitals in the same shell
(subshells)—also, gives letter
designations
 The magnetic quantum number gives
insight to the orientation of the orbital

Some ways to remember…
Principal quantum number—periods on
the periodic table
 Second quantum number—region of the
periodic table (s,p,d, or f)


Each orbital actually has a 4th quantum
number, the “spin” – we’ll learn this
tomorrow
Practice

An orbital has quantum numbers of n = 4,
l = 2, and ml = -1. Which type of orbital is
this?

How many orbitals are there in an s subshell? p sub-shell, d, f?
More practice

Which of the following represent valid
sets of quantum numbers? For a set that is
invalid, explain briefly why it is not
correct.
 n = 3, l = 3, ml = 0
 n = 2, l = 1, ml = 0
 n = 6, l = 5, ml = -1
 n = 4, l = 3, ml = -4
Don’t forget!