Transcript electronic structure 2009 notesx

Bell Task-Besides shape and color, organize your set of
items in very specific ways and list them on half slip. Dig deep
on your responses-you're advanced students!
Agenda:
·Start Chapter 5 with Periodicity
·Graphing exercise
·Class discussion about Periodic Law
Graphing exercise
Take a computer and log on
Go to Logger Pro
Look up data assigned from 3x5
card
Enter data into graph and print
Make sure graph has a specific title
State the trend on graph and
explain why the trend occurs
Share your graph with someone
and discuss
Bell task
What causes the chemical/physical properties
to repeat (Periodic Law) within the Periodic
Table?
Chemists wanted to know the answer to the
burning question above!
So, where did they start?
They began with looking at light and
other forms of energy.
What did they discover?
Electromagnetic Spectrum (EMS)collection of different kinds of radiant
energy
Frequency
wavelength
What is the
relationship
between
frequency
and
wavelength
?
EMS
is a continuous range of
wavelengths
and frequencies
Which type of electromagnetic
energy has high
frequency?
Which type of electromagnetic energy has a long
wavelength?
wavelength
measured in m or
nm-can perform a
conversion between
the two
measurements.
frequency has a
unit of hertz = s-1
how is frequency and
wavelength related?
Electromagnetic energy with a __________
wavelength has a lower frequency
electromagnetic energy with a __________
wavelength has a higher frequency
DEMO!
s
Challenge problem
The wavelength of the green light from
a traffic signal is centered at 522 nm.
What is the frequency of this radiation?
Calculate the energy in joules of a
4
photon with a wavelength of 5.00 x 10
nm (infrared region)
niels bohr and wave mechanical
model.ppt
Did you ever wonder why each principle energy
level held only so many electrons?
Example: 2-8-1 electron configuration for Na
2-8-18-7 electron configuration for Br
Where did these combinations of values come from?
Why is it that the 1st principle energy level only holds 2e? 2nd PEL only holds 8e-? etc.
Each electron in an atom has assigned to it a series
of three quantum numbers
What do the quantum numbers really represent?
(same as Principle Energy
Level)
What is the principle quantum number for Ba? Si?
Fr?
wave mechanics predicts that each main shell is composed of one or
more subshells (sublevels)
(they make up the principle energy level)
the value of l is generally
designated by letters
s,p,d,f as follows
dependent upon the value of the principle quantum
number
For a given value of n, l has possible integral values
from 0 to (n-1)
If n=1 there is only possible value of l, that is l
= 1-1 = 0
if n=2, there are two values of l that is l = 2-1
= 1 and 0
if n=3, there are three values of l, given by
0,1,2
important table
l
0
1
2
3
4
5
name of orbital
s
p
d
f
g
h
Example: the shell with n=2 is composed of two subshells,
l=0 and l=1 (s,p)
So, these subshells are called the 2s and 2p subshells
where 2 denotes the value of n and s and p denote values
of l
Principle Quantum Number, n
average distance of the electron from the
nucleus in a particular orbital
is made up of subshells, called angular
momentum quantum number, l
s, p, d, f, g, h, etc.
(so, there is only 1 orbital)
(so, there are 3 orbitals)
(so,there are 5 orbitals)
it indicates how many orbitals are located under
that particular subshell.
each subshell is
composed of one or
more orbitals.
Conclusion
:
each orbital contains only 2 e-
multiply 2
by number
of orbitals
Quantum #
Principle
Sublevel
Orbital
m
Symbol
n
l
Possible
values
1,2,3,4.......
0,1,2,3... (n-1) -l, ....0..... +1
s,p,d,f
electron/orbit
al
characteristic
Size
Shape
Orientation