Aufbau Principle
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Transcript of Aufbau Principle
Aufbau PrincipleAufbau Principle
1s2s 2p3s 3p 3d4s 4p 4d 4f5s 5p 5d 5f 5g6s 6p 6d 6f 6g 6h7s 7p 7d 7f 7g 7h 7i
e- fill lowest energy levels 1st.
nucleus
1s
2s
3s
4s
2p
3p
4p
3d
Incre
asin
g e
nerg
y
4d5s
4f5p
1
HHydrogen
1s1
2
HeHydrogen
1s2
3
LiLithium
1s22s1
4
BeBeryllium
1s22s2
5
BBoron
1s22s22p1
6
CCarbon
1s22s22p2
7
NNitrogen
1s22s22p3
8
OOxygen
1s22s22p4
9
FFluorine
1s22s22p5
10
NeNeon
1s22s22p6
11
NaSodium
[Ne]3s1
12
MgMagnesium
[Ne]3s2
13
AlAluminum
[Ne]3s23p1
14
SiSilicon
[Ne]3s23p2
15
PPhosphorus
[Ne]3s23p3
16
SSulfur
[Ne]3s23p4
17
ClChlorine
[Ne]3s23p5
18
ArArgon
[Ne]3s23p6
19
KPotassium
[Ar]4s1
20
CaCalcium
[Ar]4s2
21
ScScandium
[Ar]3d14s2
22
TiTitanium
[Ar]3d24s2
23
VVanadium
[Ar]3d34s2
24
CrChromium
[Ar]3d54s1
24
CrChromium
[Ar]3d54s1
25
MnManganese
[Ar]3d54s2
26
FeIron
[Ar]3d64s2
27
CoCobalt
[Ar]3d74s2
28
NiNickel
[Ar]3d84s2
29
CuCopper
[Ar]3d104s1
29
CuCopper
[Ar]3d104s1
30
ZnZinc
[Ar]3d104s2
31
GaGallium
[Ar]3d104s24p1
32
GeGermanium
[Ar]3d104s24p2
33
AsArsenic
[Ar]3d104s24p3
34
SeSelenium
[Ar]3d104s24p4
35
BrBromine
[Ar]3d104s24p5
36
KrKrypton
[Ar]3d104s24p6
Half-filled and filled states are preferred.
Irregular e- configurations of Cr and Cu
Chromium: A 4s electron moves to a 3d sublevel to half fill its entire 3d sublevel
Copper: A 4s electron moves to FILL its 3d sublevel
•Half filled and filled sublevels are preferred.
Orbital filling tableOrbital filling table
s1
s2
s2p1 s2p2 s2p3 s2p4 s2p5
s2p6
s2
Mendeleev’s Periodic Table (1872)Mendeleev’s Periodic Table (1872)
Dmitri Mendeleev1st to publish an organized table of elements.
Grouped elements by similar chemical properties. Arranged elements by increasing mass.
Modern Russian TableModern Russian Table
Henry Moseley (1913)Henry Moseley (1913)
Grouped elements by similar chemical properties.
Arranged elements by increasing atomic number.
Used X-Ray diffraction to determine how many protons are in an atom of an element.
The Periodic TableThe Periodic Table
PeriodGroup or Family
1
2
3
4
5
6
7
Properties of MetalloidsProperties of Metalloids
Metalloids straddle the border between metals and nonmetals on the periodic table.
Nonmetals
Metals
Metalloids
Periodic Table with Group NamesPeriodic Table with Group Names
Inner Transition Metals
Transition
Metals
Alk
ali M
eta
ls
Alk
alin
e E
art
h M
eta
ls
Halo
gen
s
Nob
le G
ases
Boro
n F
am
ily
Carb
on
Fam
ily
Nit
rog
en
Fam
ily
Oxyg
en
Fam
ily
PeriodGroup or Family
1
2
3
4
5
6
7
Trends in Atomic SizeTrends in Atomic Size
• First problem: Where do you start First problem: Where do you start measuring from?measuring from?
• The electron cloud doesn’t have a The electron cloud doesn’t have a definite edge.definite edge.
• They get around this by measuring They get around this by measuring more than 1 atom at a time.more than 1 atom at a time.
Half of the distance between nuclei in covalently bonded diatomic molecule
"covalent atomic radii"
Determination of Atomic Radius:
(e- shared)
Trends in Atomic Size Trends in Atomic Size • Influenced by three factors:Influenced by three factors:
1. Energy Level– Higher energy level is further away.Higher energy level is further away.
2. Charge on nucleus (Zeff = effective nuclear charge)
– More charge pulls electrons in closer.More charge pulls electrons in closer.3. Shielding effect– Electrons within level and from Electrons within level and from
previous levels block the effects of the previous levels block the effects of the (+) nucleus.(+) nucleus. e <-> e repulsion
Periodic TablePeriodic TableTrend forTrend for
Atomic Atomic
RadiiRadii
Size of atomdecreases
from left to right.
Size of atomincreases
from top to bottom.
Periodic Trends in Atomic Radius
Radius decreases across a period
Effective nuclear charge, Zeff, is increased. Due to: more overall charge (p+ and e-) shielding from lower levels is constant.
Group trends
• As we go down a group...
• each atom has another energy level (more shielding)
• so the atoms get bigger (Zeff is less effective).
HLi
Na
K
Rb
Periodic Trends• As you go across a period, the radius gets
smaller. (more effective nuclear charge, Zeff)
• Electrons are in same energy level.• More nuclear charge. atomic #: (p+ e-)
• Outermost electrons are closer.
Na Mg Al Si P S Cl Ar
z = 11 12 13 14 15 16 17 18
OverallOverall
Atomic Number
Ato
mic
Rad
ius
(nm
)
H
Li
Ne
Ar
10
Na
K
Kr
Rb
1st Ionization Energy - the energy required to remove the 1st electron from a mole of atoms.
375 kJ/mol Fr
He 2372 kJ/mol
376 kJ/mol Cs
403 kJ/mol Rb
419 kJ/mol K
496 kJ/mol Na
520 kJ/mol Li
1312 kJ/mol H
Ne 2081 kJ/mol
Ar 1521 kJ/mol
Kr 1351 kJ/mol
Xe 1170 kJ/mol
Rn 1037 kJ/mol
Be B C N O F
Incr
easing 1
st Ioniza
tion energ
y
Increases for successive electrons taken from the same atom
Tends to increase across a period
Electrons in the same quantum level do not shield as effectively as electrons in inner levels
Irregularities at half filled and filled sublevels due to extra repulsion of electrons paired in orbitals, making them easier to remove
Tends to decrease down a groupOuter electrons are farther from thenucleus
Ionization Energy - the energy required to remove an electron from an atom
Table of 1Table of 1stst Ionization Energies Ionization Energies
Ionization of MagnesiumIonization of Magnesium Mg + 738 kJ Mg+ + e-
Mg+ + 1451 kJ Mg2+ + e-
Mg2+ + 7733 kJ Mg3+ + e-
1st ionization energy
2nd ionization energy
3rd ionization energy
Symbol First Second ThirdHHeLiBeBCNO F Ne
1312 2731 520 900 800 1086 1402 1314 1681 2080
5247 7297 1757 2430 2352 2857 3391 3375 3963
11810 14840 3569 4619 4577 5301 6045 6276
Symbol First Second ThirdHHeLiBeBCNO F Ne
1312 2731 520 900 800 1086 1402 1314 1681 2080
5247 7297 1757 2430 2352 2857 3391 3375 3963
11810 14840 3569 4619 4577 5301 6045 6276
ElectronegativityElectronegativity
A measure of the ability of an atom in a chemicalcompound to attract electrons
Electronegativities tend to increase across a period
Electronegativities tend to decrease down a group or remain the same
Periodic Table of ElectronegativitiesPeriodic Table of Electronegativities
Increasing electronegativ
ity
Summation of Periodic TrendsSummation of Periodic Trends
Ionic RadiiIonic Radii
Cations
Positively charged ions formed when an atom of a metal loses one or more electrons Smaller than the corresponding atom
Anions
Negatively charged ions formed when nonmetallic atoms gain one or more electrons Larger than the corresponding atom
Ion radius
Atom radius
Shielding
• The electron in the The electron in the outermost energy level outermost energy level experiences more inter-experiences more inter-electron repulsion electron repulsion (shielding).(shielding).
• Second electron has same Second electron has same shielding, if it is in the shielding, if it is in the same periodsame period
Group trends• As you go down a group, first IE As you go down a group, first IE
decreases because...decreases because...• The electron is further away.The electron is further away.• More shielding.More shielding.
Periodic trends
• All the atoms in the same period have All the atoms in the same period have the same energy level.the same energy level.
• Same shielding.Same shielding.• But, increasing nuclear chargeBut, increasing nuclear charge• So IE generally increases from left to So IE generally increases from left to
right.right.• Exceptions at full and 1/2 full orbitals.Exceptions at full and 1/2 full orbitals.
Firs
t Ion
izat
ion
ener
gy
Atomic number
He
• He has a greater IE than H.He has a greater IE than H.• same shielding same shielding • greater nuclear chargegreater nuclear charge
H
1s 2s 2pnucleus
electrons
Orbital diagram
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He Li has lower IE than H Outer electron further
away outweighs greater
nuclear charge
Li
1s 2s 2pnucleus
electrons
Orbital diagram
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He Be has higher IE than Li same shielding greater nuclear charge
Li
Be
1s 2s 2p
electrons
Orbital diagram
nucleus
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He B has lower IE than Be same shielding greater nuclear charge p orbital is slightly more
diffuse and its electron easier to remove
Li
Be
B
1s 2s 2p
electrons
nucleus
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
1s 2s 2p
electrons
nucleus
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
1s 2s 2pnucleus
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
O
• Breaks the pattern, because the outer electron is paired in a p orbital and experiences inter-electron repulsion.
1s 2s 2pnucleus
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
O
F
1s 2s 2pnucleus
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
O
F
Ne• Ne has a lower IE Ne has a lower IE
than Hethan He• Both are full,Both are full,• Ne has more Ne has more
shieldingshielding• Greater distanceGreater distance
1s 2s 2pnucleus
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
O
F
Ne Na has a lower IE than
Li Both are s1
Na has more shielding Greater distance
Na
Firs
t Ion
izat
ion
ener
gy
Atomic number
Table of 1Table of 1stst Ionization Energies Ionization Energies