No office hours today!. What’s coming up??? Oct 25The atmosphere, part 1Ch. 8 Oct 27Midterm … No...
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Transcript of No office hours today!. What’s coming up??? Oct 25The atmosphere, part 1Ch. 8 Oct 27Midterm … No...
•No office hours today!
What’s coming up???• Oct 25 The atmosphere, part 1 Ch. 8• Oct 27 Midterm … No lecture• Oct 29 The atmosphere, part 2 Ch. 8• Nov 1 Light, blackbodies, Bohr Ch. 9• Nov 3,5 Postulates of QM, p-in-a-box Ch. 9• Nov 8,10Hydrogen and multi – e atoms Ch. 9• Nov 12, 15 Multi-electron atoms Ch.9,10• Nov 17 Periodic properties Ch. 10• Nov 19 Periodic properties Ch. 10• Nov 22 Valence-bond; Lewis structures Ch. 11• Nov 24 Hybrid orbitals; VSEPR Ch. 11, 12• Nov 26 VSEPR Ch. 12• Nov 29 MO theory Ch. 12• Dec 1 MO theory Ch. 12• Dec 2 Review for exam
Hydrogen has its one electron in the 1s orbital:1s 2s 2p
H:
1s 2s 2p
He:
1s 2s 2p
He:
helium ground state
Helium has two electrons:
1s1
1s12s1
1s2
ORBITAL DIAGRAM
Now onto the next atoms
Helium can also exist in an excited state such as:
with opposite spins:
both occupy the 1s orbitalPauli principle
Lithium has three electrons, so it must use the 2s orbital:
Beryllium has four electrons, which fill both the 1s and 2s
orbitals:
Boron’s five electrons fill the 1s and 2s orbitals, and
begin to fill the 2p orbitals. Since all three are degenerate,
the order in which they are filled does not matter.
1s 2s 2p
Li: 1s22s1
1s 2s 2p
Be: 1s2 2s2
1s 2s 2p
B: 1s22s22p1
1s 2s 2p
C: 1s22s22p2
1s 2s 2p
C: 1s22s22p2
How can we decide?????
A CHOICE
OR
CARBON Z=6
HUND’S RULEFOR THE GROUND STATE
ELECTRONS OCCUPY DEGENERATE ORBITALS SEPARATELY
THE SPINS ARE PARALLEL
SO FOR CARBON THE GROUND STATE IS
1s 2s 2p
C: 1s22s22p2
1s 2s 2p
Ne: 1s22s22p6
1s 2s 2p
F: 1s22s22p5
1s 2s 2p
O: 1s22s22p4
1s 2s 2p
N: 1s22s22p3
Nitrogen
Oxygen
Fluorine
Neon
THE ELECTRON CONFIGURATIONS FOR NITROGEN TO NEON
The valence electron configuration of the elements
in the periodic table repeat periodically!
H He1s1 1s2
Li Be B C N O F Ne2s1 2s2 2p1 2p2 2p3 2p4 2p5 2p6
Na Mg Al Si P S Cl Ar3s1 3s2 3p1 3p2 3p3 3p4 3p5 3p6
Every element in a group has
the same valence electron configuration!
Sodium has the electron configuration
Na: 1s22s22p63s1
abbreviate electron configurations by ...
1s22s22p63s23p64s23d104p65s1And Rb is:
dividing the electrons into……..
valence electrons and core electrons.
What does this mean?????
Example Na: 1s22s22p63s1
VALENCE ELECTRONS
Noble gases have fully-filled valence shells
Example Ar: 1s22s22p63s23p6
are the electrons in the outermost principle
quantum level of an atom.
highest value of n.
Valence electrons are the ones involved in bonding.
CORE ELECTRONS
can be abbreviated as a noble gas core and
the valence electrons.
The configuration for sodium is:
Na: 1s22s22p63s1
or Na: [Ne]3s1
ELECTRON CONFIGURATIONS
Now we can easily write the electron configurations…..
QUESTION…..
1s
E
2s2p
3s3p
3d4s
4p5s
4d
POTASSIUM ELECTRONIC CONFIGURATION
1s22s22p62p23s23p64s1 or [Ar]4s1
Q: why does 3d lie above 4s??
SCREENING AND PENETRATION
PENETRATION Is to get close to the nucleus
SCREENING Is to block the view of other electrons of the nucleus
Consider the excited state of helium
1s13p1
LOOK AT RADIAL PROBABILITY DISTRIBUTIONS
0
0.1
0.2
0.3
0.4
0.5
0.6
0 5 10 15 20 25 30
SCREENING AND PENETRATION
THE 1s close to the nucleus
PENETRATES WELL SEES A CHARGE OF Z=2
EFFECTIVE NUCLEAR CHARGE…...
Is
3p
THE 3p DOES NOT SCREEN THE NUCLEUS
0
0.1
0.2
0.3
0.4
0.5
0.6
0 5 10 15 20 25 30
SCREENING AND PENETRATION
THE 1s close to the nucleus
EFFECTIVE NUCLEAR CHARGE Zeff = 2
ENERGY MORE NEGATIVE THAN IN H-ATOM
Is
3p
E 2.178 x 10-19n
Z
neff2
0
0.1
0.2
0.3
0.4
0.5
0.6
0 5 10 15 20 25 30
SCREENING AND PENETRATION
THE 3p far from the nucleus
PENETRATES POORLY 1s SCREENS 3p WELL
SEES A CHARGE OF Zeff = Z – S = 2-1 = 1
Is
3p
0
0.02
0.04
0.06
0.08
0.1
0.12
0 5 10 15 20 25 30
THE 3s orbital penetrates better than 3p orbital
3s
3p
3d
The 3p orbital penetrates better than 3d orbital
Zeff(s) > Zeff(p) > Zeff(d)
0
0.05
0.1
0.15
0.2
0.25
0 5 10 15 20 25 30
So, in a multi-electron atom Zeff(s) > Zeff(p) > Zeff(d)
E4s < E3d
ENERGY LEVELS REVERSE!!E A
Z
nneff 2
2
The first transition element is scandium, Sc (Z=21)
H He1s1 1s2
Li Be B C N O F Ne2s1 2s2 2p1 2p2 2p3 2p4 2p5 2p6
Na Mg Al Si P S Cl Ar3s1 3s2 3p1 3p2 3p3 3p4 3p5 3p6
K Ca
Scandium has the electron configuration:
Sc: [Ar]4s23d1
Sc
TRANSITION METALS.
Because…..
1s
E
2s2p
3s3p
3d4s
4p5s
4d
ENERGY LEVEL DIAGRAM FOR A MULTI-ELECTRON ATOM
SCANDIUM ELECTRONIC CONFIGURATION
Scandium is the first TRANSITION ELEMENT
Sc: [Ar]4s23d1
the metals that fill the d orbitals in their valence
shell.
TRANSITION METALS
HUND’S RULE OBEYED FOR ALL EXCEPT
Cr and Cu
Cr: [Ar] 4s23d4EXPECTED
OBSERVED Cr: [Ar] 4s13d5 …. The d-shell is ½ filled this way; all spin up
WHEN n=3
FOR COPPER
the metals that fill the d orbitals in their valence
shell.
TRANSITION METALS
HUND’S RULE OBEYED FOR ALL EXCEPT
Cr and Cu
Cu: [Ar] 4s23d9EXPECTED
OBSERVED Cu: [Ar] 4s13d10 …. The d-shell is filled this way – extra stable
WHEN n=3
IONS…...