wavelength
The Periodic Table
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Electronic Structures of Atoms
Where are the e ’s located and how are they arranged?
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How can we probe an atom to find out?
“Let’s use light.”
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The Electromagnetic Spectrum:
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Light travels in waves: wavelength (
) frequency: how many wavelengths pass through a fixed point each second. cycles/sec = Hertz (Hz) = 1/s = s -1
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c =
frequency (s -1 or 1/s) (cycles per s or hz) wavelength speed of light: 3.00 x 10 8 m/s
Calculate the frequency of red light having a wavelength of 700 nm.
3.0
x 10
8 m s 700 x 10 -9 m
4.28 x 10 14 s or 4.28 x 10 14 s -1
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Light travels in waves:
Which wavelength has the most energy?
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Photoelectric effect: e -
Metal surface
Light of the right frequency (energy) can strike a metal and cause an electron to be ejected (n = infinity) .
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10
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The nucleous
The first layer of e
-
’ s e
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“Energy is quantized”
“light energy particles are called photons”
E = h
frequency
Planck’s constant = 6.63 x 10 -34 J•s
Energy
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c =
E = h
frequency (s -1 or 1/s) (cycles per s or hz) wavelength speed of light: 3.00 x 10 8 m/s frequency
Planck’s constant = 6.63 x 10
-
34 J•s
Energy
Together they lead to: E
hc
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red:
Calculate the energy of red light vs. blue light .
red light: 700 nm blue light: 400 nm
E
hc
E
hc
blue: E
hc
E
( 6 .
62 x 10
34
J
s )(
700 x 10
3
9
.
00 m x 10
8 m / s )
E
( 6 .
62 x 10
34
J
s )(
400 x 10
3
9
.
00 m x 10
8 m / s )
E = 2.85 x 10 -19 J E = 4.96 x 10 -19 J sunburn????? uv
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Hydrogen only four lines are observed
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Paschen series infrared
Balmer series (visible)
Lyman series (ultraviolet)
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E
n
R
H
1 n
2
R
H
= 2.18 x 10 -18 J
Rydberg constant
E
E f
E i
h
h
E
R
H h
1 n 2 i
1 n 2 f
Can be used to find the energy between levels.
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type
Quantum Numbers: n = principle quantum no.
values
1,2,3,etc meaning shell (period) l = angular momentum quant. # or azimuthal q# m l
= magnetic q. #
0,1,2,3...
s,p,d,f,g,h..
0,
1,
2,
3,..
subshell orbital m s
= spin q. #
½ spin
These 4 Quantum numbers give the general location of electrons within an atom and the general shape of the orbital in which they reside.
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It is really an address system to write to electrons.
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If you become frightened, close your eyes and repeat:
“It’s only model” until you are once again calm.
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n = 4
4 subshells f (7 orbitals) d (5 orbitals) f d f d f f d f d f d p (3 orbitals) p x s (1 orbital) n = 3
3 subshells d (5 orbitals) p (3orbitals) s (1 orbital) n=2
2 subshells p (3 orbitals)
+ d p x p x d p d p p s s y y y d p p p z z z d s (1 orbital) s subshell n=1 (1st shell)
1 subshell s (1 orbital) s subshell only holds 2 electrons
Gives: "electron Address" = (n)energy , (l)shape of house (orbital),
(m l
) which , spin f n = 4, l = 2, m n = 4, l = 0, m l l
= +2
= 0 n = 2, l = 1, m l
= -1
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n = 4
4 subshells f (7 orbitals) d (5 orbitals) f d f d f f d f d f d p (3 orbitals) p x s (1 orbital) n = 3
3 subshells d (5 orbitals) p (3orbitals) s (1 orbital) n=2
2 subshells p (3 orbitals)
+ d p x p x d p d p p s s y y y d p p p z z z d s (1 orbital) s subshell n=1 (1st shell)
1 subshell s (1 orbital) s subshell only holds 2 electrons
Gives: "electron Address" = (n)energy , (l)shape of house (orbital),
(m l
) which , spin f n = 4 l = 3 m l
=-3,-2,-1,0,1,2,3 l = 2 l = 1 l = 0 m l
=-2,-1,0,1,2 m l
=-1,0,1 m l
=0 n = 3 l = 2 l = 1 l = 0 n = 2 n =1
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n = 4
4 subshells f (7 orbitals) d (5 orbitals) f d f d f p (3 orbitals) p x s (1 orbital) n = 3
3 subshells d (5 orbitals) p (3orbitals) s (1 orbital) n=2
2 subshells p (3 orbitals)
+ d p x p x d f d p y s d p y s p y f d d f p z p z p z d d f
Each compartment (orbital) can only hold two electrons.
Pauli exclusion principle: no 2 e ’s in the same atom can have the same 4 quantum numbers.
Hund’s rule: each orbital of a subshell will get 1 e of parallel spin before they are paired.
n = 2, l =1, m l
=+1, m s
= -1/2 s (1 orbital) s subshell n=1 (1st shell)
1 subshell s (1 orbital) s subshell only holds 2 electrons
Gives: "electron Address" = (n)energy , (l)shape of house (orbital),
(m l
) which , spin
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Orbital Shapes
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Filling Orders
let’s use the periodic table to write out filling orders.
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The Periodic Table
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