1 © 2009 brooks/cole - cengage test ii raw grades: hi92 lo9 average:37.3 curve 25 pt. grades...
TRANSCRIPT
1
© 2009 Brooks/Cole - Cengage
Test IITest II
Raw grades:Raw grades:HiHi 9292LoLo 99Average:Average: 37.337.3Curve Curve 25 pt.25 pt.
Grades (curved) are posted on BlazeVIEWGrades (curved) are posted on BlazeVIEWLook at tests/ask questions after class or Look at tests/ask questions after class or Wednesday 9 – 1pm (in my office)Wednesday 9 – 1pm (in my office)
Analysis/solutions session can be scheduled if Analysis/solutions session can be scheduled if there is interest (there is interest (email [email protected])email [email protected])
2
© 2009 Brooks/Cole - Cengage
Midterm GradesMidterm Grades
Based only on Test 1 (75.7%) and Based only on Test 1 (75.7%) and OWL (24.2%)OWL (24.2%)
The last day to drop without academic penalty: The last day to drop without academic penalty: March 3d, by 11:59 pm; March 3d, by 11:59 pm; limited to five withdrawals per college lifelimited to five withdrawals per college life
3
© 2009 Brooks/Cole - Cengage
Chapter 6Chapter 6
Chem 1211
Class 13
Atomic Structure
4
© 2009 Brooks/Cole - Cengage
Atomic Line Spectra and Atomic Line Spectra and Niels BohrNiels Bohr
Atomic Line Spectra and Atomic Line Spectra and Niels BohrNiels Bohr
Bohr’s theory was a great Bohr’s theory was a great accomplishment.accomplishment.
Rec’d Nobel Prize, 1922Rec’d Nobel Prize, 1922
Problems with theory —Problems with theory —
• theory only successful for H.theory only successful for H.
• introduced quantum idea introduced quantum idea artificially.artificially.
• So, we go on to So, we go on to QUANTUMQUANTUM or or WAVE MECHANICSWAVE MECHANICSNiels BohrNiels Bohr
(1885-1962)(1885-1962)
5
© 2009 Brooks/Cole - Cengage
Quantum or Wave Quantum or Wave MechanicsMechanics
Quantum or Wave Quantum or Wave MechanicsMechanics
de Broglie (1924) de Broglie (1924) proposed that all proposed that all moving objects have moving objects have wave properties. wave properties.
For light: E = mcFor light: E = mc22
E = hE = h = = hc / hc /
Therefore, mc = h / Therefore, mc = h / and for particlesand for particles
(mass)(velocity) = (mass)(velocity) = h / h /
de Broglie (1924) de Broglie (1924) proposed that all proposed that all moving objects have moving objects have wave properties. wave properties.
For light: E = mcFor light: E = mc22
E = hE = h = = hc / hc /
Therefore, mc = h / Therefore, mc = h / and for particlesand for particles
(mass)(velocity) = (mass)(velocity) = h / h /
L. de BroglieL. de Broglie(1892-1987)(1892-1987)
6
© 2009 Brooks/Cole - Cengage
Baseball (115 g) Baseball (115 g) at 100 mphat 100 mph
= 1.3 x 10= 1.3 x 10-32-32 cm cm
e- with velocity e- with velocity = =
1.9 x 101.9 x 1088 cm/sec cm/sec
= 3.88 x 10= 3.88 x 10-10-10 m m = 0.388 nm= 0.388 nm
Experimental proof of waveExperimental proof of waveproperties of electronsproperties of electrons
Quantum or Wave Quantum or Wave MechanicsMechanics
Quantum or Wave Quantum or Wave MechanicsMechanics
PLAY MOVIE
7
© 2009 Brooks/Cole - Cengage
Uncertainty PrincipleUncertainty PrincipleProblem of defining Problem of defining nature of electrons in nature of electrons in atoms solved by W. atoms solved by W. Heisenberg.Heisenberg.
Cannot simultaneously Cannot simultaneously define the position and define the position and momentum (= m•v) of an momentum (= m•v) of an electron.electron.
We define e- energy We define e- energy exactly but accept exactly but accept limitation that we do limitation that we do not know exact not know exact position.position.
Problem of defining Problem of defining nature of electrons in nature of electrons in atoms solved by W. atoms solved by W. Heisenberg.Heisenberg.
Cannot simultaneously Cannot simultaneously define the position and define the position and momentum (= m•v) of an momentum (= m•v) of an electron.electron.
We define e- energy We define e- energy exactly but accept exactly but accept limitation that we do limitation that we do not know exact not know exact position.position.
W. HeisenbergW. Heisenberg1901-19761901-1976
8
© 2009 Brooks/Cole - Cengage
Schrodinger applied idea of Schrodinger applied idea of e- behaving as a wave to e- behaving as a wave to the problem of electrons in the problem of electrons in atoms.atoms.
He developed the He developed the WAVE WAVE EQUATIONEQUATION
Solution gives set of math Solution gives set of math expressions called expressions called WAVE WAVE FUNCTIONS, FUNCTIONS, psipsi))
Each describes an allowed Each describes an allowed energy state of an e-energy state of an e-
Quantization introduced Quantization introduced naturally.naturally.
E. SchrodingerE. Schrodinger1887-19611887-1961
Quantum or Wave Quantum or Wave MechanicsMechanics
Quantum or Wave Quantum or Wave MechanicsMechanics
9
© 2009 Brooks/Cole - Cengage
WAVE FUNCTIONS, WAVE FUNCTIONS,
• is a function of distance and two is a function of distance and two angles.angles.
• • Each Each corresponds to an corresponds to an ORBITALORBITAL — — the region of space within which an the region of space within which an electron is found.electron is found.
• • does NOT describe the exact does NOT describe the exact location of the electron.location of the electron.
• • 22 is proportional to the probability is proportional to the probability of finding an e- at a given point.of finding an e- at a given point.
There is a set of numbers that are There is a set of numbers that are
parameters of parameters of : they are called : they are called quantum quantum numbersnumbers
10
© 2009 Brooks/Cole - Cengage
QUANTUM NUMBERSQUANTUM NUMBERSQUANTUM NUMBERSQUANTUM NUMBERS
The The shape, size, and energyshape, size, and energy of each orbital is a of each orbital is a function of 3 quantum numbers:function of 3 quantum numbers:
nn (principal)(principal) →→ shell shell
ll (angular) (angular) → → subshellsubshell
mmll (magnetic)(magnetic) → → designates an orbital designates an orbital within a subshellwithin a subshell
According to that numbers, electrons in atom According to that numbers, electrons in atom grouped in shells and subshellsgrouped in shells and subshells
11
© 2009 Brooks/Cole - Cengage
Subshells & Subshells & ShellsShells
Subshells & Subshells & ShellsShells
• Subshells grouped in shells.Subshells grouped in shells.• Each shell has a number called Each shell has a number called
thethe PRINCIPAL QUANTUM PRINCIPAL QUANTUM NUMBER, NUMBER, nn
• The principal quantum number The principal quantum number of the shell is the number of the of the shell is the number of the period or row of the periodic period or row of the periodic table where that shell begins.table where that shell begins.
12
© 2009 Brooks/Cole - Cengage
Subshells & Subshells & ShellsShells
Subshells & Subshells & ShellsShells
n = 1n = 1
n = 2n = 2
n = 3n = 3
n = 4n = 4
13
© 2009 Brooks/Cole - Cengage
Types of Types of OrbitalsOrbitals
s orbitals orbital p orbitalp orbital d orbitald orbital
14
© 2009 Brooks/Cole - Cengage
OrbitalsOrbitals• No more than 2 e- assigned to an orbitalNo more than 2 e- assigned to an orbital
• Orbitals grouped in s, p, d (and f) Orbitals grouped in s, p, d (and f) subshellssubshells
s orbitalss orbitals
d orbitalsd orbitals
p orbitalsp orbitals
15
© 2009 Brooks/Cole - Cengage
s orbitalss orbitals
d orbitalsd orbitals
p orbitalsp orbitals
s orbitalss orbitals p orbitalsp orbitals d orbitalsd orbitals
No.No.orbs.orbs.
No. No. e-e-
11 33 55
22 66 1010
16
© 2009 Brooks/Cole - Cengage
SymbolSymbol ValuesValues DescriptionDescription
n (major)n (major) 1, 2, 3, ..1, 2, 3, .. Orbital size Orbital size and energy and energy
where E = -R(1/nwhere E = -R(1/n22))
ll (angular)(angular) 0, 1, 2, .. n-10, 1, 2, .. n-1 Orbital shape Orbital shape or type or type (subshell) (subshell)
mmll (magnetic) (magnetic) -l..-l..0..+0..+ll Orbital Orbital orientationorientation
# of orbitals in subshell = # of orbitals in subshell = 22ll + 1 + 1
QUANTUM NUMBERSQUANTUM NUMBERS
17
© 2009 Brooks/Cole - Cengage
Types of
Atomic Orbitals
See Active Figure 6.14
18
© 2009 Brooks/Cole - Cengage
Shells and SubshellsShells and SubshellsShells and SubshellsShells and Subshells
When n = 1, thenWhen n = 1, then ll = 0 and m= 0 and mll = 0 = 0
Therefore, in n = 1, there is 1 Therefore, in n = 1, there is 1 type of type of subshellsubshell
and that subshell has a single and that subshell has a single orbitalorbital
(m(mll has a single value has a single value →→ 1 orbital) 1 orbital)
This subshell is labeled This subshell is labeled ss (“ess”) (“ess”)
Each shell has 1 orbital labeled s, Each shell has 1 orbital labeled s, and it is and it is SPHERICALSPHERICAL in shape.in shape.
19
© 2009 Brooks/Cole - Cengage
s Orbitals— Always s Orbitals— Always SphericalSpherical
Dot picture Dot picture of electron of electron cloud in 1s cloud in 1s orbital.orbital.
Surface Surface densitydensity
4πr4πr22 versus versus distancedistance
Surface of Surface of 90% 90% probabiliprobability sphere ty sphere
See Active Figure 6.13
20
© 2009 Brooks/Cole - Cengage
1s Orbital1s Orbital
21
© 2009 Brooks/Cole - Cengage
2s Orbital2s Orbital
22
© 2009 Brooks/Cole - Cengage
3s Orbital3s Orbital
23
© 2009 Brooks/Cole - Cengage
p Orbitalsp Orbitalsp Orbitalsp OrbitalsWhen n = 2, then When n = 2, then ll = 0 and = 0 and 11
Therefore, in n = 2 shell Therefore, in n = 2 shell there are 2 types of there are 2 types of orbitals — 2 subshellsorbitals — 2 subshells
For For ll = 0 = 0 mmll = 0 = 0
this is a s subshellthis is a s subshell
For For ll = 1 = 1 mmll = -1, 0, +1 = -1, 0, +1
this is a this is a p p subshellsubshell with with
3 orbitals3 orbitals
When n = 2, then When n = 2, then ll = 0 and = 0 and 11
Therefore, in n = 2 shell Therefore, in n = 2 shell there are 2 types of there are 2 types of orbitals — 2 subshellsorbitals — 2 subshells
For For ll = 0 = 0 mmll = 0 = 0
this is a s subshellthis is a s subshell
For For ll = 1 = 1 mmll = -1, 0, +1 = -1, 0, +1
this is a this is a p p subshellsubshell with with
3 orbitals3 orbitals
planar node
Typical p orbital
planar node
Typical p orbital
See Screen 6.15See Screen 6.15
When When ll = 1, there is = 1, there is a a PLANARPLANAR NODENODE thru the thru the nucleus.nucleus.
24
© 2009 Brooks/Cole - Cengage
p Orbitalsp Orbitalsp Orbitalsp Orbitals
The three p orbitals lie 90The three p orbitals lie 90oo apart in space apart in space
25
© 2009 Brooks/Cole - Cengage
2p2pxx Orbital Orbital 3p3pxx Orbital Orbital
26
© 2009 Brooks/Cole - Cengage
d Orbitalsd Orbitalsd Orbitalsd OrbitalsWhen n = 3, what are the values of When n = 3, what are the values of ss??
ll = 0, 1, 2 = 0, 1, 2 and so there are 3 subshells in the and so there are 3 subshells in the shell.shell.
For For ll = 0, = 0, mmll = 0 = 0
→→ s subshell with single s subshell with single orbitalorbital
For For ll = 1, = 1, mmll = -1, 0, +1 = -1, 0, +1
→→ p subshell with 3 orbitalsp subshell with 3 orbitals
For For ll = 2, = 2, mm l l = -2, -1, 0, +1, +2= -2, -1, 0, +1, +2
→→d subshell with 5 d subshell with 5 orbitalsorbitals
27
© 2009 Brooks/Cole - Cengage
d Orbitalsd Orbitalsd Orbitalsd Orbitals
s orbitals have no s orbitals have no planar node (planar node (ll = 0) = 0) and so are spherical.and so are spherical.
p orbitals have p orbitals have ll = 1, = 1, and have 1 planar and have 1 planar node,node,
and so are “dumbbell” and so are “dumbbell” shaped.shaped.
This means d orbitals This means d orbitals (with (with ll = 2) have 2 = 2) have 2 planar nodesplanar nodes
typical d orbital
planar node
planar node
See Figure 6.15See Figure 6.15See Figure 6.15See Figure 6.15
28
© 2009 Brooks/Cole - Cengage
3d3dxyxy Orbital Orbital
29
© 2009 Brooks/Cole - Cengage
3d3dxzxz Orbital Orbital
30
© 2009 Brooks/Cole - Cengage
3d3dyzyz Orbital Orbital
31
© 2009 Brooks/Cole - Cengage
3d3dxx22
- y- y22 Orbital Orbital
32
© 2009 Brooks/Cole - Cengage
3d3dzz22 Orbital Orbital
33
© 2009 Brooks/Cole - Cengage
f Orbitalsf Orbitalsf Orbitalsf OrbitalsWhen n = 4, When n = 4, ll = 0, 1, 2, 3 so there are 4 = 0, 1, 2, 3 so there are 4 subshells in the shell.subshells in the shell.
For For ll = 0, m = 0, mll = 0 = 0
→ → s subshell with single orbitals subshell with single orbital
For For ll = 1, m = 1, mll = -1, 0, +1 = -1, 0, +1
→ → p subshell with 3 orbitalsp subshell with 3 orbitals
For For ll = 2, m = 2, mll = -2, -1, 0, +1, +2 = -2, -1, 0, +1, +2
→ → d subshell with 5 orbitalsd subshell with 5 orbitals
For For ll = 3, m = 3, mll = -3, -2, -1, 0, +1, +2, = -3, -2, -1, 0, +1, +2, +3+3
→ → f subshell with 7 f subshell with 7 orbitalsorbitals
34
© 2009 Brooks/Cole - Cengage
f Orbitalsf Orbitals
One of 7 possible f orbitals.
All have 3 planar nodal surfaces.
Can you find the 3 surfaces here?
35
© 2009 Brooks/Cole - Cengage
Spherical NodesSpherical Nodes
•Orbitals also have spherical Orbitals also have spherical nodesnodes•Number of spherical nodes Number of spherical nodes = n - = n - ll - 1 - 1•For a 2s orbital:For a 2s orbital: No. of nodes = 2 - 0 - 1 = 1 No. of nodes = 2 - 0 - 1 = 1
2 s orbital
36
© 2009 Brooks/Cole - Cengage
Arrangement of Arrangement of Electrons in AtomsElectrons in Atoms
Arrangement of Arrangement of Electrons in AtomsElectrons in Atoms
Electrons in atoms are arranged asElectrons in atoms are arranged as
SHELLSSHELLS (n) (n)
SUBSHELLSSUBSHELLS ( (ll))
ORBITALSORBITALS (m (mll))