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Greek Model
• Greek philosopher• Idea of ‘democracy’• Idea of ‘atomos’
– Atomos = ‘indivisible’– ‘Atom’ is derived
• No experiments to support idea
• Continuous vs. discontinuous theory of matter
Democritus’s model of atom
No protons, electrons, or neutrons
Solid and INDESTRUCTABLE
Democritus
“To understand the very large,
we must understand the very small.”
Foundations of Atomic Theory
Law of Definite Proportions
The fact that a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound.
Law of Multiple Proportions
If two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first elements is always a ratio of small whole numbers.
Law of Conservation of Mass
Mass is neither destroyed nor created during ordinary chemical reactions.
45 g H2O? g H2O
Conservation of Mass
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 204
Highvoltage
Before reaction
electrodes
glasschamber
5.0 g H2
80 g O2
300 g (mass of chamber)+385 g total
H2O2
Highvoltage
After reaction
0 g H2
40 g O2
300 g (mass of chamber)+385 g total
O2
H2O
Law of Definite ProportionsJoseph Louis Proust (1754 – 1826)
• Each compound has a specific ratio of elements
• It is a ratio by mass • Water is always 8 grams of oxygen for
every one gram of hydrogen
The Law of Multiple Proportions
• Dalton could not use his theory to determine the elemental compositions of chemical compounds because he had no reliable scale of atomic masses.
• Dalton’s data led to a general statement known as the law of multiple proportions.
• Law states that when two elements form a series of compounds, the ratios of the masses of the second element that are present per gram of the first element can almost always be expressed as the ratios of integers.
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
Crookes Tube
William Crookes
Mask holder
Cathode(-)
Anode(+)
Crookes tube(Cathode ray tube)
Mask holder
Glow
Cathode Rays
• Cathode ray = electron
• Electrons have a negative charge
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, pages 117-118
Highvoltage
cathode
source ofhigh voltage
yellow-greenfluorescence
shadow
(A) The effect of an obstruction on cathode rays
(B) The effect of an electric field on cathode rays
Highvoltage
cathode
source ofhigh voltage
positiveplate
negative plate
anode
source oflow voltage
+
-
J.J. Thomson• He proved that atoms of
any element can be made to emit tiny negative particles.
• From this he concluded that ALL atoms must contain these negative particles.
• He knew that atoms did not have a net negative charge and so there must be balancing the negative charge.
J.J. Thomson
William Thomson (Lord Kelvin)
• In 1910 proposed the Plum Pudding model– Negative electrons
were embedded into a positively charged spherical cloud.
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 56
Spherical cloud ofPositive charge
Electrons
Rutherford’s Apparatus
beam of alpha particles
radioactive substance
gold foil
circular ZnS - coated
fluorescent screen
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 120
Rutherford received the 1908 Nobel Prize in Chemistry for his pioneering work in nuclear chemistry.
Geiger-Muller Counter
Speaker gives“click” for
each particle
Window
Particlepath
Argon atoms
Hans Geiger
Rutherford’sGold-Leaf Experiment
Conclusions:
Atom is mostly empty space
Nucleus has (+) charge
Electrons float around nucleus
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 120
Bohr’s Model
Nucleus
Electron
Orbit
Energy Levels
Bohr Model of Atom
The Bohr model of the atom, like many ideas in the history of science, was at first prompted by and later partially disproved by experimentation.
http://en.wikipedia.org/wiki/Category:Chemistry
Increasing energyof orbits
n = 1
n = 2
n = 3
A photon is emittedwith energy E = hf
e-e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
An unsatisfactory model for the hydrogen atom
According to classical physics, lightshould be emitted as the electron circles the nucleus. A loss of energywould cause the electron to be drawncloser to the nucleus and eventuallyspiral into it.
Hill, Petrucci, General Chemistry An Integrated Approach 2nd Edition, page 294
Quantum Mechanical Model
Modern atomic theory describes the electronic structure of the atom as the probability of finding electrons within certain regions of space (orbitals).
Niels Bohr &Albert Einstein
Models of the Atom
Dalton’s model (1803)
Thomson’s plum-pudding model (1897)
Rutherford’s model (1909)
Bohr’s model (1913)
Charge-cloud model (present)
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 125
Greek model(400 B.C.)
+--
--
-e
e
e
+
+ +
+
++
++
e
ee
e
e
ee
"In science, a wrong theory can be valuable and better than no theory at all."- Sir William L. Bragg
Electrons (-) charge no mass located outside the nucleus
Protons (+) charge 1 amu located inside the nucleus
Neutrons no charge 1 amu located inside the nucleus
Particles in the Atom
Discovery of the Neutron
James Chadwick bombarded beryllium-9 with alpha particles, carbon-12 atoms were formed, and neutrons were emitted.
n10
+He42
+Be94 C12
6
Dorin, Demmin, Gabel, Chemistry The Study of Matter 3rd Edition, page 764 *Walter Boethe
Subatomic particles
Electron
Proton
Neutron
Name Symbol ChargeRelative mass
Actual mass (g)
e-
p+
no
-1
+1
0
1/1840
1
1
9.11 x 10-28
1.67 x 10-24
1.67 x 10-24
Symbols
Contain the symbol of the element, the mass number and the atomic number
X Massnumber
Atomicnumber
# protons
# protons + # neutrons mass number
Symbols
• Find the – number of protons– number of neutrons– number of electrons– Atomic number– Mass number
F19 9
= 9
= 10
= 9
= 9
= 19
+
Symbols
Find the – number of protons– number of neutrons– number of electrons– Atomic number– Mass number
Na2311
Sodium atom
= 11
= 12
= 11
= 11
= 23
Symbols
Find the – number of protons– number of neutrons– number of electrons– Atomic number– Mass number
Na2311
1+
Sodium ion
= 11
= 12
= 10
= 11
= 23
3545358035Br
1822184018Ar
2020204020Ca
e–n0p+MassAtomic
Ca40.08
20
Ar39.948
18
Br79.904
35
3 p+
4 n0 2e– 1e–
Li shorthand
Bohr - Rutherford diagrams• Putting all this together, we get B-R diagrams• To draw them you must know the # of protons, neutrons,
and electrons (2,8,8,2 filling order)• Draw protons (p+), (n0) in circle (i.e. “nucleus”)• Draw electrons around in shells
2 p+
2 n0
He
3 p+
4 n0
Li
Draw Be, B, Al and shorthand diagrams for O, Na
11 p+12 n°
2e– 8e– 1e–
Na
8 p+8 n°
2e– 6e–
O
4 p+5 n°
Be
5 p+6 n°
B
13 p+14 n°
Al
Mass Number
• mass # = protons + neutrons
• always a whole number
• NOT on the Periodic Table!
+
+
+
+
+
+
Nucleus
Electrons
Nucleus
Neutron
Proton
Carbon-12Neutrons 6Protons 6Electrons 6
e-
e-
e-
e-
e-
e-
Isotopes
• Atoms of the same element with different mass numbers.
Mass #
Atomic #
• Nuclear symbol:
• Hyphen notation: carbon-12Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
12
6 C
3 p+
3 n02e– 1e– 3 p+
4 n02e– 1e–
6Li 7Li
+
+
+Nucleus
Electrons
Nucleus
Neutron
Proton
Lithium-6Neutrons 3Protons 3Electrons 3
Nucleus
Electrons
Nucleus
Neutron
Proton
Lithium-7Neutrons 4Protons 3Electrons 3
+
+
+
Average Atomic Mass
• weighted average of all isotopes• on the Periodic Table• round to 2 decimal places
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Avg.AtomicMass
= (mass)(%) + (mass)(%)
100
Average Atomic Mass
• EX: Calculate the avg. atomic mass of oxygen if its abundance in nature is 99.76% 16O, 0.04% 17O, and 0.20% 18O.
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Avg.AtomicMass
= (16)(99.76) + (17)(0.04) + (18)(0.20)
100= 16.00
amu
Average Atomic Mass
• EX: Find chlorine’s average atomic mass if approximately 8 of every 10 atoms are chlorine-35 and 2 are chlorine-37.
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Avg.AtomicMass
= (35)(8) + (37)(2)
10= 35.40 amu
100
90
80
70
60
50
40
30
20
10
034 35 36 37
Ab
un
dan
ce
Mass
Mass spectrum of chlorine. Elemental chlorine (Cl2) contains only two isotopes: 34.97 amu (75.53%) and 36.97 (24.47%)
AAM = (34.97 amu)(0.7553) + (36.97 amu)(0.2447)
AAM = (26.412841 amu) + (9.046559 amu)
AAM = 35.4594 amu
Cl-35
Cl-37
Cl35.4594
17
Mass Spectrometry
- +
Photographic plate
196 199 201 204
198 200 202
Mass spectrum of mercury vapor
Hill, Petrucci, General Chemistry An Integrated Approach 1999, page 320
Stream of positive ions
Mass Spectrum for Mercury
196 197 198 199 200 201 202 203 204
Mass number
Rel
ativ
e n
umb
er o
f at
oms
30
25
20
15
10
5
196 199 201 204
198 200 202
Mass spectrum of mercury vapor
The percent natural abundances for mercury isotopes are:
Hg-196 0.146% Hg-198 10.02% Hg-199 16.84% Hg-200 23.13% Hg-201 13.22% Hg-202 29.80% Hg-204 6.85%
(The photographic record has been converted to a scale of relative number of atoms)
The percent natural abundances for mercury isotopes are:
Hg-196 0.146% Hg-198 10.02% Hg-199 16.84% Hg-200 23.13% Hg-201 13.22% Hg-202 29.80% Hg-204 6.85%
(0.00146)(196) + (0.1002)(198) + (0.1684)(199) + (0.2313)(200) + (0.1322)(201) + (0.2980)(202) + (0.0685)(204) = x
0.28616 + 19.8396 + 33.5116 + 46.2600 + 26.5722 + 60.1960 + 13.974 = x
x = 200.63956 amu
Hg200.59
80
(% "A")(mass "A") + (% "B")(mass "B") + (% "C")(mass "C") + (% "D")(mass "D") + (% "E")(mass "E") + (% F)(mass F) + (% G)(mass G) = AAM
ABCDEFG
Natural uranium, atomic weight = 238.029 g/molDensity is 19 g/cm3. Melting point 1000oC.
Two main isotopes:
U238 92
U235 92
99.3%
0.7%
Because isotopes are chemically identical(same electronic structure), they cannot beseparated by chemistry.
So Physics separates them by diffusion orcentrifuge (mass spectrograph is too slow)…
Separation of Isotopes
(238 amu) x (0.993) + (235 amu) x (0.007)
236.334 amu + 1.645 amu
237.979 amu
U238
92
• Assume you have only two atoms of chlorine.• One atom has a mass of 35 amu (Cl-35)• The other atom has a mass of 36 amu (Cl-36)
• What is the average mass of these two isotopes?
35.5 amu
• Looking at the average atomic mass printed on the periodic table...approximately what percentage is Cl-35 and Cl-36?
55% Cl-35 and 45% Cl-36 is a good approximation
Cl35.453
17
Using our estimated % abundance data
55% Cl-35 and 45% Cl-36
calculate an average atomic mass for chlorine.
Cl35.453
17
Average Atomic Mass = (% abundance of isotope "A")(mass "A") + (% "B")(mass "B")
AAM = (% abundance of isotope Cl-35)(mass Cl-35) + (% abundance of Cl-36)(mass Cl-36)
AAM = (0.55)(35 amu) + (0.45)(36 amu)
AAM = (19.25 amu) + (16.2 amu)
AAM = 35.45 amu
Isotopes
Dalton was wrong.
Atoms of the same element can have different numbers of neutrons
different mass numbers
called isotopes
California WEB
C-12 vs. C-14
Using a periodic table and what you know about atomic number, mass, isotopes, and electrons, fill in the chart:
Element Symbol AtomicNumber
AtomicMass
# of protons
# of neutron
# of electron
charge
8 8 8
Potassium 39 +1
Br 45 -1
30 35 30
Atomic Number = Number of Protons
Number of Protons + Number of Neutrons = Atomic Mass
Atom (no charge) : Protons = Electrons
Ion (cation) : Protons > Electrons Ion (anion) : Electrons > Protons
Periodic Table
• Dmitri Mendeleev developed the modern periodic table.
• Argued that element properties are periodic functions of their atomic weights.
• We now know that element properties are periodic functions of their ATOMIC NUMBERS.
Atomic Mass
Magnesium has three isotopes. 78.99% magnesium 24 with a mass of 23.9850 amu, 10.00% magnesium 25 with a mass of 24.9858 amu, and the rest magnesium 26 with a mass of 25.9826 amu. What is the atomic mass of magnesium?
If not told otherwise, the mass of the isotope is
the mass number in amu.
California WEB
IsotopePercent
AbundanceMass
Mg-24 78.99 23.9850
Mg-25 10.00 24.9585
Mg-26 25.9826
24.304 amu
18.94575
2.49585
2.8606811.01
Atomic Mass
Calculate the atomic mass of copper if copper has two isotopes. 69.1% has a mass of 62.93 amu and the rest has a mass of 64.93 amu.
... )B"" )(massB"" (% )A"" )(massA"" (% (AAM) massatomic Average
Copper for amu 63.548 A.A.M.
amu 20.06337 amu 43.48463 A.A.M.
amu) .93(0.309)(64 amu) .93(0.691)(62 A.A.M.
Cu29
63.548
IsotopePercent
AbundanceMass
Cu-63 69.1 62.93
Cu-65 64.93
43.48463
20.0633730.9
63.548
Given the average atomic mass of an element is 118.21 amu and it has three isotopes (“A”, “B”, and “C”):
isotope “A” has a mass of 117.93 amu and is 87.14% abundantisotope “B” has a mass of 120.12 amu and is 12.36% abundant
Find the mass of isotope “C”. Show work for credit.
Extra Credit: What is a cation?
A positively charged atom. An atom that has lost a(n) electron(s).
119.7932 amu
Protons Neutrons ElectronsMass
number
Cu-65 A = 29 B = 36 29 C = 65
Argon D = 18 E = 22 F = 18 40
Ba2+ 56 G = 81 H = 54 I = 137
Quantum Mechanics
• Heisenberg Uncertainty Principle– Impossible to know both the velocity and
position of an electron at the same time
Microscope
Electron
g
Werner Heisenberg~1926
Quantum Mechanics
σ3/2 Zπ
11s 0
eΨ a
• Schrödinger Wave Equation (1926)
– finite # of solutions quantized energy levels
– defines probability of finding an electron
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Erwin Schrödinger~1926
Quantum Mechanics
• Orbital (“electron cloud”)– Region in space where there is 90%
probability of finding an electron
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Electron Probability vs. Distance
Ele
ctro
n P
roba
bilit
y (%
)
Distance from the Nucleus (pm)
100 150 200 2505000
10
20
30
40
Orbital
90% probability offinding the electron
Quantum Numbers
UPPER LEVEL
• Four Quantum Numbers:– Specify the “address” of each electron
in an atom
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Quantum Numbers
Principal Quantum Number ( n )
Angular Momentum Quantum # ( l )
Magnetic Quantum Number ( ml )
Spin Quantum Number ( ms )
Quantum Numbers
1. Principal Quantum Number ( n )
– Energy level
– Size of the orbital
– n2 = # of orbitals in the energy level
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
1s
2s
3s
Shapes of s, p, and d-Orbitals
s orbital
p orbitals
d orbitals
Atomic Orbitals
s, p, and d-orbitals
As orbitals:
Hold 2 electrons(outer orbitals ofGroups 1 and 2)
Bp orbitals:
Each of 3 pairs oflobes holds 2 electrons
= 6 electrons(outer orbitals of Groups 13 to 18)
Cd orbitals:
Each of 5 sets oflobes holds 2 electrons
= 10 electrons(found in elements
with atomic no. of 21and higher)
Kelter, Carr, Scott, , Chemistry: A World of Choices 1999, page 82
Quantum Numbers
px pz py
x
y
z
x
y
z
x
y
z
Quantum Numbers
• n = # of sublevels per level• n2 = # of orbitals per level• Sublevel sets: 1 s, 3 p, 5 d, 7 f
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
n = 3n = 2n = 1Principallevel
Sublevel
Orbital
s s p s p d
px py pz dxy dxz dyz dz2 dx2- y2px py pz
Maximum Capacities of Subshells and Principal Shells
n 1 2 3 4 ...n
l 0 0 1 0 1 2 0 1 2 3
Subshelldesignation s s p s p d s p d f
Orbitals insubshell 1 1 3 1 3 5 1 3 5 7
Subshellcapacity 2 2 6 2 6 10 2 6 10 14
Principal shellcapacity 2 8 18 32 ...2n2
Hill, Petrucci, General Chemistry An Integrated Approach 1999, page 320
Quantum Numbers
3. Magnetic Quantum Number ( ml )– Orientation of orbital
– Specifies the exact orbital within each sublevel
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
The magnetic quantum number
Third quantum is ml, the magnetic quantum number
– Value of ml describes the orientation of the region in space occupied by the electrons with respect
to an applied magnetic field
– Allowed values of ml depend on the value of l
– ml can range from –l to l in integral steps ml = l, -l + l, . . . 0 . . ., l – 1, l
– Each wave function with an allowed combination of n, l, and ml values describes an atomic orbital, a particular spatial distribution for
an electron
– For a given set of quantum numbers, each principal shell contains a fixed number of subshells, and each subshell contains a fixed number of orbitals
Copyright © 2006 Pearson Benjamin Cummings. All rights reserved.
Principal Energy Levels 1 and 2
Quantum Numbers
4. Spin Quantum Number ( ms )– Electron spin +½ or -½
– An orbital can hold 2 electrons that spin in opposite directions.
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Electron Spin: The Fourth Quantum Number
• When an electrically charged object spins, it produces a magnetic moment parallel to the axis of rotation and behaves like a magnet.
• A magnetic moment is called electron spin.
• An electron has two possible orientations in an external magnetic field, which are described by a fourth quantum number ms.
• For any electron, ms can have only two possible values, designated + (up) and – (down), indicating that the two orientations are opposite and the subscript s is for spin.
• An electron behaves like a magnet that has one of two possible orientations, aligned either with the magnetic field or against it.
Copyright © 2006 Pearson Benjamin Cummings. All rights reserved.
Quantum Numbers
1. Principal # 2. Ang. Mom. # 3. Magnetic # 4. Spin #
energy level
sublevel (s,p,d,f)
orbital
electron
• Pauli Exclusion Principle– No two electrons in an atom can have the
same 4 quantum numbers.
– Each electron has a unique “address”:
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Wolfgang Pauli
Level n 1 2 3
Sublevel l Orbital ml
Spin ms
0 0
0 0 1 0 -1 0 1 0 -1 2 1 0 -1 -2
2101
= +1/2
= -1/2
Allowed Sets of Quantum Numbers for Electrons in Atoms
H = 1s1
1s
He = 1s2
1s
Li = 1s2 2s1
1s 2s
Be = 1s2 2s2
1s 2s
C = 1s2 2s2 2p2
1s 2s 2px 2py 2pz
S = 1s2 2s2 2p6
3s2 3p41s 2s 2px 2py 2pz 3s 3px 3py 3pz
THIS SLIDE IS ANIMATEDIN FILLING ORDER 2.PPT
Fe = 1s1 2s22p63s23p64s23d6
1s 2s 2px 2py 2pz 3s 3px 3py 3pz
+26
e-
e-
e-
e-
4s 3d 3d 3d 3d
Iron has ___ electrons.26
3d
ArbitraryEnergy Scale
18
18
32
8
8
2
1s
2s 2p
3s 3p
4s 4p 3d
5s 5p 4d
6s 6p 5d 4f
NUCLEUS
e-
e-e-
e-
e- e-
e-
e-
e-
e-
e-
e-
e-e-
e-
e-
e-
e-
e- e-
e-
e-
Orbital Filling
Element 1s 2s 2px 2py 2pz 3s Configuration
Electron ConfigurationsElectron
H
He
Li
C
N
O
F
Ne
Na
1s1
1s22s22p63s1
1s22s22p6
1s22s22p5
1s22s22p4
1s22s22p3
1s22s22p2
1s22s1
1s2
Filling Rules for Electron Orbitals
Aufbau Principle: Electrons are added one at a time to the lowest energy orbitals available until all the electrons of the atom have been accounted for.
Pauli Exclusion Principle: An orbital can hold a maximum of two electrons.To occupy the same orbital, two electrons must spin in opposite directions.
Hund’s Rule: Electrons occupy equal-energy orbitals so that a maximum number of unpaired electrons results.
*Aufbau is German for “building up”
Spin Quantum Number, ms
North
South
The electron behaves as if it were spinning about an axis through its center.This electron spin generates a magnetic field, the direction of which dependson the direction of the spin.
Brown, LeMay, Bursten, Chemistry The Central Science, 2000, page 208
- -S
N
Electron aligned with magnetic field,
ms = + ½
Electron aligned against magnetic field,
ms = - ½
Energy Level Diagram of a Many-Electron Atom
ArbitraryEnergy Scale
18
18
32
8
8
2
1s
2s 2p
3s 3p
4s 4p 3d
5s 5p 4d
6s 6p 5d 4f
NUCLEUS
O’Connor, Davis, MacNab, McClellan, CHEMISTRY Experiments and Principles 1982, page 177
Maximum Number of Electrons In Each SublevelMaximum Number of Electrons In Each Sublevel
Maximum Number Sublevel Number of Orbitals of Electrons
s 1 2
p 3 6
d 5 10
f 7 14
LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 146
Quantum Numbers
n shell
l subshell
ml orbital
ms electron spin
1, 2, 3, 4, ...
0, 1, 2, ... n - 1
- l ... 0 ... +l
+1/2 and - 1/2
Order in which subshells are filled with electrons
1s
2s
3s
4s
5s
6s
7s
2p
3p
4p
5p
6p
3d
4d
5d
6d
4f
5f
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d … 2 2 6 2 6 2 10 6 2 10
4f
4d
4p
4s
n = 4
3d
3p
3s
n = 3
2p
2s
n = 2
1sn = 1
En
erg
y
Sublevels
2s
3s
4s
5s
6s
7s
1s
2p
3p
4p
5p
6p
3d
4d
5d
6d
4f
5f
1s
2s2p
3s
3p4s
4p3d
4d5s
5p6s
7s6p
6d
4f
5f
5d
En
erg
y
4f
4d
4p
4s
n = 4
3d
3p
3s
n = 3
2p
2s
n = 2
1sn = 1
En
erg
y
Sublevels
s
s
s
s
p
p
p
d
d f
1s22s22p63s23p64s23d104p65s24d10…
Filling Rules for Electron Orbitals
Aufbau Principle: Electrons are added one at a time to the lowest energy orbitals available until all the electrons of the atom have been accounted for.
Pauli Exclusion Principle: An orbital can hold a maximum of two electrons.To occupy the same orbital, two electrons must spin in opposite directions.
Hund’s Rule: Electrons occupy equal-energy orbitals so that a maximum number of unpaired electrons results.
*Aufbau is German for “building up”
Energy Level Diagram of a Many-Electron Atom
ArbitraryEnergy Scale
18
18
32
8
8
2
1s
2s 2p
3s 3p
4s 4p 3d
5s 5p 4d
6s 6p 5d 4f
NUCLEUS
O’Connor, Davis, MacNab, McClellan, CHEMISTRY Experiments and Principles 1982, page 177
Energy Level Diagram
Arb
itrar
y E
nerg
y S
cale
1s
2s 2p
3s 3p
4s 4p 3d
5s 5p 4d
6s 6p 5d 4f
NUCLEUS
CLICK ON ELEMENT TO FILL IN CHARTS
Fe = 1s22s22p63s23p64s23d6
N
H He Li C N Al Ar F Fe La
Bohr Model
Iron
Electron Configuration
Energy Level Diagram
Arb
itrar
y E
nerg
y S
cale
1s
2s 2p
3s 3p
4s 4p 3d
5s 5p 4d
6s 6p 5d 4f
NUCLEUS
CLICK ON ELEMENT TO FILL IN CHARTS
La = 1s22s22p63s23p64s23d10
4s23d104p65s24d105p66s25d1
N
H He Li C N Al Ar F Fe La
Bohr Model
Lanthanum
Electron Configuration
neon's electron configuration (1s22s22p6)
Shorthand Configuration
[Ne] 3s1
third energy level
one electron in the s orbital
orbital shape
Na = [1s22s22p6] 3s1 electron configuration
A
B
C
D
Shorthand Configuration
[Ar] 4s2
Electron configurationElement symbol
[Ar] 4s2 3d3
[Rn] 7s2 5f14 6d4
[He] 2s2 2p5
[Kr] 5s2 4d9
[Kr] 5s2 4d10 5p5
[Kr] 5s2 4d10 5p6
[He] 2s22p63s23p64s23d6
Ca
V
Sg
F
Ag
I
Xe
Fe [Ar] 4s23d6
[Kr] 5s1 4d10
General Rules
Aufbau Principle– Electrons fill the
lowest energy orbitals first.
– “Lazy Tenant Rule”
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
2s
3s
4s
5s
6s
7s
1s
2p
3p
4p
5p
6p
3d
4d
5d
6d
4f
5f
1s
2s
2p
3s
3p
4s
4p
3d
4d5s
5p6s
7s
6p
6d
4f
5f
5d
En
erg
y
RIGHTWRONG
General Rules
• Hund’s Rule– Within a sublevel, place one electron
per orbital before pairing them.
– “Empty Bus Seat Rule”
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
• Shorthand Configuration
S 16e-
Valence ElectronsCore Electrons
S 16e- [Ne] 3s2 3p4
1s2 2s2 2p6 3s2 3p4
Notation
• Longhand Configuration
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
S32.066
16
sp
d (n-1)
f (n-2) 67
Periodic Patterns
1s
2s
3s
4s
5s
6s
7s
3d
4d
5d
6d
1s
2p
3p
4p
5p
6p
7p
4f
5f
1234567
s-block1st Period
1s11st column of s-block
1
2
3
4
5
6
7
Periodic Patterns
• Example - Hydrogen
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
1
2
3
4
5
6
7
Periodic Patterns
• Shorthand Configuration– Core electrons:
• Go up one row and over to the Noble Gas.
– Valence electrons: • On the next row, fill in the # of e- in each sublevel.
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
• Full energy level
1
2
3
4
5
6
7
• Full sublevel (s, p, d, f)• Half-full sublevel
Stability
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
This fills the valenceshell and tends to givethe atom the stabilityof the inert gasses.
The Octet Rule
Atoms tend to gain, lose, or share electrons until they have eight valence electrons.
8
ONLY s- and p-orbitals are valence electrons.
• Electron Configuration Exceptions– Copper
EXPECT: [Ar] 4s2 3d9
ACTUALLY: [Ar] 4s1 3d10
– Copper gains stability with a full d-sublevel.
Stability
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Electron Filling in Periodic Table
K4s1
Ca4s2
Sc3d1
Ti3d2
V3d3
Mn3d5
Fe3d6
Co3d7
Ni3d8
Cr3d4
Cu3d9
Zn3d10
Ga4p1
Ge4p2
As4p3
Se4p4
Br4p5
Kr4p6
1
2
3
4
s
d
p
s
Cr4s13d5
Cu4s13d10
4f
4d
4p
4s
n = 4
3d
3p
3s
n = 3
2p
2sn = 2
1sn = 1
Ene
rgy
4s 3d
Cr4s13d5
4s 3d
Cu4s13d10
Cr3d5
Cu3d10
1
2
3
4 5
6
7
Stability
• Ion Formation– Atoms gain or lose electrons to become more
stable.– Isoelectronic with the Noble Gases.
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Orbital Diagrams for Nickel
2s 2p 3s 3p 4s 3d1s
2s 2p 3s 3p 4s 3d1s
2s 2p 3s 3p 4s 3d1s
2s 2p 3s 3p 4s 3d1s
Excited State
VIOLATES Pauli Exclusion
VIOLATES Hund’s Rule
Ni58.6934
28
2 2 6 2 6 2 8
2 2 6 2 6 1 9
Write out the complete electron configuration for the following:1) An atom of nitrogen
2) An atom of silver
3) An atom of uranium (shorthand)
Fill in the orbital boxes for an atom of nickel (Ni)
2s 2p 3s 3p 4s 3d1s
Which rule states no two electrons can spin the same direction in a single orbital?
1s22s22p3
1s22s22p63s23p64s23d104p65s24d9
[Rn]7s26d15f3
Extra credit: Draw a Bohr model of a Ti4+ cation. 22+n = n
Pauli exclusion principle
Ti4+ is isoelectronic to Argon.
Answer Key
Orbitals Being Filled
1s
2s
3s
4s
5s
6s
7s
3d
4d
5d
6d
2p
3p
4p
5p
6p
1s
La
Ac
1
3 4 5 6 7
4f
5f
Lanthanide series
Actinide series
Groups 8
Per
iod
s
1 2
2
3
4
5
6
7
Li
3
H
1
He
2
C
6
N
7
O
8
F
9
Ne
10
Na
11
B
5
Be
4
H
1
Al
13
Si
14
P
15
S
16
Cl
17
Ar
18
K
19
Ca
20
Sc
21
Ti
22
V
23
Cr
24
Mn
25
Fe
26
Co
27
Ni
28
Cu
29
Zn
30
Ga
31
Ge
32
As
33
Se
34
Br
35
Kr
36
Rb
37
Sr
38
Y
39
Zr
40
Nb
41
Mo
42
Tc
43
Ru
44
Rh
45
Pd
46
Ag
47
Cd
48
In
49
Sn
50
Sb
51
Te
52
I
53
Xe
54
Cs
55
Ba
56
Hf
72
Ta
73
W
74
Re
75
Os
76
Ir
77
Pt
78
Au
79
Hg
80
Tl
81
Pb
82
Bi
83
Po
84
At
85
Rn
86
Fr
87
Ra
88
Rf
104
Db
105
Sg
106
Bh
107
Hs
108
Mt
109
Mg
12
Ce
58
Pr
59
Nd
60
Pm
61
Sm
62
Eu
63
Gd
64
Tb
65
Dy
66
Ho
67
Er
68
Tm
69
Yb
70
Lu
71
Th
90
Pa
91
U
92
Np
93
Pu
94
Am
95
Cm
96
Bk
97
Cf
98
Es
99
Fm
100
Md
101
No
102
Lr
103
La
57
Ac
89
1
2
3
4
5
6
7
s
d
p
s
f
*
W
W
*
Electron Filling in Periodic Table
K4s1
Ca4s2
Sc3d1
Ti3d2
V3d3
Mn3d5
Fe3d6
Co3d7
Ni3d8
Cr3d4
Cu3d9
Zn3d10
Ga4p1
Ge4p2
As4p3
Se4p4
Br4p5
Kr4p6
1
2
3
4
s
d
p
s
Cr4s13d5
Cu4s13d10
4f
4d
4p
4s
n = 4
3d
3p
3s
n = 3
2p
2sn = 2
1sn = 1
Ene
rgy
4s 3d
Cr4s13d5
4s 3d
Cu4s13d10
Cr3d5
Cu3d10
Electron Configurations of First 18 Elements:Hydrogen
1H
Lithium
3Li
Sodium
11NaMagnesium
12Mg
Boron
5B
Aluminum
13Al
Carbon
6C
Silicon
14SiPhosphorous
15P
Oxygen
8O
Sulfur
16S
Fluorine
9F
Chlorine
17Cl
Neon
10Ne
Argon
18Ar
Beryllium
4BeNitrogen
7N
Helium
2He
Electron Dot Diagrams
H
Li
Na
K
Be
Mg
Ca
B
Al
Ga
C
Si
Ge
N
P
As
O
S
Se
F
Cl
Br
Ne
Ar
Kr
He
Group
1A 2A 3A 4A 5A 6A 7A 8A
= valence electron
s1 s2 s2p2 s2p3 s2p4 s2p5 s2p6s2p1
1 2 13 14 15 16 17 18
First Four Energy Levels
n = 1
n = 2
n = 3
n = 4
Ene
rgy
Sublevels
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 334
1s
2s 2p
3s 3p 3d
4s4p 4d 4f
Sublevel designation
Four sublevels
Three sublevels
Two sublevels
One sublevel
Principallevel 4
Principallevel 3
Principallevel 2
Principallevel 1
Principal Level 2 Divided
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 334
2s
2s sublevel 2p sublevel
2px 2py 2pz
4f
4d
4p
4s
n = 4
3d
3p
3s
n = 3
2p
2s
n = 2
1sn = 1
En
erg
y
Sublevels
Four sublevels
Three sublevels
Two sublevels
One sublevel
Principallevel 4
Principallevel 3
Principallevel 2
Principallevel 1
Metals and Nonmetals
Li
3
He
2
C
6
N
7
O
8
F
9
Ne
10
Na
11
B
5
Be
4
H
1
Al
13
Si
14
P
15
S
16
Cl
17
Ar
18
K
19
Ca
20
Sc
21
Ti
22
V
23
Cr
24
Mn
25
Fe
26
Co
27
Ni
28
Cu
29
Zn
30
Ga
31
Ge
32
As
33
Se
34
Br
35
Kr
36
Rb
37
Sr
38
Y
39
Zr
40
Nb
41
Mo
42
Tc
43
Ru
44
Rh
45
Pd
46
Ag
47
Cd
48
In
49
Sn
50
Sb
51
Te
52
I
53
Xe
54
Cs
55
Ba
56
Hf
72
Ta
73
W
74
Re
75
Os
76
Ir
77
Pt
78
Au
79
Hg
80
Tl
81
Pb
82
Bi
83
Po
84
At
85
Rn
86
Fr
87
Ra
88
Rf
104
Db
105
Sg
106
Bh
107
Hs
108
Mt
109
Mg
12
Ce
58
Pr
59
Nd
60
Pm
61
Sm
62
Eu
63
Gd
64
Tb
65
Dy
66
Ho
67
Er
68
Tm
69
Yb
70
Lu
71
Th
90
Pa
91
U
92
Np
93
Pu
94
Am
95
Cm
96
Bk
97
Cf
98
Es
99
Fm
100
Md
101
No
102
Lr
103
La
57
Ac
89
1
2
3
4
5
6
7
*
W
METALS
Nonmetals
Metalloids
Isotopes of Magnesium
Atomic symbol Mg Mg Mg
Number of protons 12 12 12
Number of electrons 12 12 12
Mass number 24 25 26
Number of neutrons 12 13 14
2412
2512
2612
Isotope Notation Mg-24 Mg-25 Mg-26
Timberlake, Chemistry 7th Edition, page 64
12p+
12n0
12p+
13n0
12p+
14n0
12e- 12e- 12e-
Isotopes of Hydrogen
1 p+ 1 e- 1 p+
1 n 1 e- 1 p+2 n 1 e-
Protium Deuterium Tritium
(ordinary hydrogen) (heavy hydrogen) (radioactive hydrogen)
H1
1H2
1H3
1
Ralph A. Burns, Fundamentals of Chemistry 1999, page 100
H-2 H-3H-1
Isotopes of Three Common Elements
Element SymbolFractional
AbundanceAverage Atomic Mass
Carbon
Chlorine
SiliconSiSiSi
282930
27.97728.97629.974
92.21% 4.70% 3.09%
12 6
13 6
3517
3717
2814
2914
3014
12.01
35.45
28.09
1.11%13.00313C
98.89%12 (exactly)12C
Mass (amu)
75.53%
24.47%36.96637Cl
34.96935Cl
Mass
Number
LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 110
Atomic Structure
• ATOMS– Differ by number of protons
• IONS– Differ by number of electrons
• ISOTOPES– Differ by number of neutrons
Formation of Cation
11p+
sodium atomNa
e-
loss of one valence
electron
e-
e-
e-
e-e-
e-
e-
e- e-
e-
sodium ionNa+
11p+e-
e-
e-
e-e-
e-
e-
e-
e-
e-
e-
Formation of Anion
17p+
chlorine atomCl
e-
e-
e-
e-
e-e-
e-
e-
e- e-
e-
e-
e-
e-
e-
e-
e-
e-
gain of one valence
electron
chloride ionCl1-
17p+e-
e-
e-
e-e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
Formation of Ionic Bond
chloride ionCl1-
sodium ionNa+
11p+e-
e-
e-
e-e-
e-
e-
e-
e-
e-
17p+e-
e-
e-
e-e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-