atomic orbital and electronic configurations
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ATOMIC ATOMIC ORBITAL & ORBITAL & ELECTRON ELECTRON
CONFIGURATIOCONFIGURATIONN
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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
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Subshells & Subshells & ShellsShells
Subshells & Subshells & ShellsShells
n = 1n = 1
n = 2n = 2
n = 3n = 3
n = 4n = 4
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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:
n n (major)(major) ---> shell---> shell
ll (angular) (angular) ---> subshell---> subshell
mmll (magnetic)(magnetic) ---> designates an orbital ---> designates an orbital within a subshellwithin a subshell
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SymbolSymbol ValuesValues DescriptionDescription
nn (major) (major) 1, 2, 3, ...1, 2, 3, ... Orbital Orbital sizesize, , energyenergy, and, and
# of nodes# of nodes=n-1=n-1
ll (angular) (angular) 0, 1, 2, ... n-10, 1, 2, ... n-1 Orbital Orbital shapeshape or type or type
(subshell) (subshell)
mmll (magnetic) (magnetic) -l,...0,...+l -l,...0,...+l Orbital Orbital orientationorientation
# of orbitals in subshell = 2 l + 1# of orbitals in subshell = 2 l + 1
QUANTUM NUMBERSQUANTUM NUMBERS
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Shells and SubshellsShells and SubshellsShells and SubshellsShells and Subshells
When When n = 1n = 1, then , then l = 0l = 0 and and mmll = 0 = 0
Therefore, in n = 1, there is 1 type of Therefore, in n = 1, there is 1 type of subshellsubshell
and that subshell has a single orbitaland that subshell has a single orbital
(m(mll=0 has a single value ---> 1 orbital)=0 has a single value ---> 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.
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s Orbitalss Orbitalss Orbitalss Orbitals
All s orbitals are All s orbitals are spherical in spherical in shapeshape..
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1s Orbital1s Orbital
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2s Orbital2s Orbital
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3s Orbital3s Orbital
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p Orbitalsp Orbitalsp Orbitalsp OrbitalsWhen n = 2, then l = 0 and l = 1When n = 2, then l = 0 and l = 1
Therefore, when n = 2 there are Therefore, when n = 2 there are 2 types of orbitals — 2 2 types of orbitals — 2 subshellssubshells
For For l = 0l = 0mmll = 0, = 0, s subshells subshell
For For l = 1l = 1 m mll = -1, 0, +1 = -1, 0, +1
this is a this is a p subshellp subshell with with 3 orbitals3 orbitals
When n = 2, then l = 0 and l = 1When n = 2, then l = 0 and l = 1
Therefore, when n = 2 there are Therefore, when n = 2 there are 2 types of orbitals — 2 2 types of orbitals — 2 subshellssubshells
For For l = 0l = 0mmll = 0, = 0, s subshells subshell
For For l = 1l = 1 m mll = -1, 0, +1 = -1, 0, +1
this is a this is a p subshellp subshell with with 3 orbitals3 orbitals
planar node
Typical p orbital
planar node
Typical p orbital
See Screen 7.13See Screen 7.13
When l = 1, there is aWhen l = 1, there is a
NODAL PLANENODAL PLANE
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p Orbitalsp Orbitalsp Orbitalsp Orbitals
• The three p orbitals are oriented 90The three p orbitals are oriented 90oo apart apart in spacein space
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d Orbitalsd Orbitalsd Orbitalsd Orbitals
When n = 3, what are the values of l?When n = 3, what are the values of l?
l = 0, 1, 2 l = 0, 1, 2 and so there are 3 subshells in the shell.and so there are 3 subshells in the shell.
For l = 0, mFor l = 0, mll = 0 = 0
---> s subshell with single orbital---> s subshell with single orbital
For l = 1, mFor l = 1, mll = -1, 0, +1 = -1, 0, +1
---> p subshell with 3 orbitals---> p subshell with 3 orbitals
For l = 2, mFor l = 2, mll = -2, -1, 0, +1, +2 = -2, -1, 0, +1, +2
---> ---> d subshell with 5 orbitalsd subshell with 5 orbitals
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d Orbitalsd Orbitalsd Orbitalsd Orbitals
s orbitals have no planar s orbitals have no planar node (l = 0) and so are node (l = 0) and so are spherical.spherical.
p orbitals have l = 1, and p orbitals have l = 1, and have 1 planar node,have 1 planar node,
and so are “dumbbell” and so are “dumbbell” shaped.shaped.
This means d orbitals (with This means d orbitals (with l = 2) have l = 2) have
2 planar nodes2 planar nodes
typical d orbital
planar node
planar node
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3d3dxyxy Orbital Orbital
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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 (l) (l)
ORBITALSORBITALS (m (mll))
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Each orbital can be assigned no Each orbital can be assigned no
more than 2 electrons!more than 2 electrons!
This is tied to the existence of a 4th This is tied to the existence of a 4th
quantum number, the quantum number, the electron electron
spin quantum number, mspin quantum number, mss..
Arrangement of Arrangement of Electrons in AtomsElectrons in Atoms
Arrangement of Arrangement of Electrons in AtomsElectrons in Atoms
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Electron Electron Spin Spin
Quantum Quantum Number, Number,
mmss
Can be proved experimentally that electronCan be proved experimentally that electronhas a spin. Two spin directions are given byhas a spin. Two spin directions are given bymmss where m where mss = +1/2 and -1/2. = +1/2 and -1/2.
Can be proved experimentally that electronCan be proved experimentally that electronhas a spin. Two spin directions are given byhas a spin. Two spin directions are given bymmss where m where mss = +1/2 and -1/2. = +1/2 and -1/2.
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n ---> shelln ---> shell 1, 2, 3, 4, ...1, 2, 3, 4, ...
l ---> subshelll ---> subshell 0, 1, 2, ... n - 10, 1, 2, ... n - 1
mmll ---> orbital ---> orbital -l ... 0 ... +l-l ... 0 ... +l
mmss ---> electron spin ---> electron spin +1/2 and -1/2+1/2 and -1/2
n ---> shelln ---> shell 1, 2, 3, 4, ...1, 2, 3, 4, ...
l ---> subshelll ---> subshell 0, 1, 2, ... n - 10, 1, 2, ... n - 1
mmll ---> orbital ---> orbital -l ... 0 ... +l-l ... 0 ... +l
mmss ---> electron spin ---> electron spin +1/2 and -1/2+1/2 and -1/2
QUANTUMQUANTUMNUMBERSNUMBERSQUANTUMQUANTUMNUMBERSNUMBERS
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Pauli Exclusion Pauli Exclusion PrinciplePrinciple
No two electrons in the No two electrons in the same atom can have the same atom can have the same set of 4 quantum same set of 4 quantum numbers.numbers.
That is, each electron in an That is, each electron in an atom has a unique address atom has a unique address of quantum numbers.of quantum numbers.
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Electrons in AtomsElectrons in AtomsElectrons in AtomsElectrons in Atoms
When n = 1, then l = 0When n = 1, then l = 0
this shell has a single orbital (1s) to this shell has a single orbital (1s) to
which 2e- can be assigned.which 2e- can be assigned.
When n = 2, then l = 0, 1When n = 2, then l = 0, 1
2s orbital 2s orbital 2e-2e-
three 2p orbitalsthree 2p orbitals 6e-6e-
TOTAL = TOTAL = 8e-8e-
22Assigning Electrons to Assigning Electrons to
SubshellsSubshells• In H atom all subshells of In H atom all subshells of
same n have same same n have same energy.energy.
• In many-electron atom:In many-electron atom:a) subshells increase in a) subshells increase in
energy as value of (n + l) energy as value of (n + l) increases.increases.
b) for subshells of same b) for subshells of same (n + l), the subshell with (n + l), the subshell with
lower n is lower in lower n is lower in energy.energy.
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Electron Electron Filling Filling OrderOrder
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Writing Atomic Electron Writing Atomic Electron ConfigurationsConfigurations
Writing Atomic Electron Writing Atomic Electron ConfigurationsConfigurations
1111 ss
value of nvalue of nvalue of lvalue of l
no. ofno. ofelectronselectrons
spdf notationspdf notationfor H, atomic number = 1for H, atomic number = 1
Two ways of Two ways of writing configs. writing configs. One is called One is called the the spdf spdf notation.notation.
Two ways of Two ways of writing configs. writing configs. One is called One is called the the spdf spdf notation.notation.
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Writing Atomic Electron Writing Atomic Electron ConfigurationsConfigurations
Writing Atomic Electron Writing Atomic Electron ConfigurationsConfigurations
Two ways of Two ways of writing writing configs. Other configs. Other is called the is called the orbital box orbital box notation.notation.
Two ways of Two ways of writing writing configs. Other configs. Other is called the is called the orbital box orbital box notation.notation.
Arrowsdepictelectronspin
ORBITAL BOX NOTATIONfor He, atomic number = 2
1s
21 s
Arrowsdepictelectronspin
ORBITAL BOX NOTATIONfor He, atomic number = 2
1s
21 s
One electron has n = 1, l = 0, mOne electron has n = 1, l = 0, m ll = 0, m = 0, mss = + 1/2 = + 1/2
Other electron has n = 1, l = 0, mOther electron has n = 1, l = 0, m ll = 0, m = 0, mss = - 1/2 = - 1/2