Download Chapter 4-Arrangement of Electrons in Atoms

Chapter 4-Arrangement of
Electrons in Atoms
Carbon:1s22s22p2
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Bell Ringer
• Locate the worksheet entitled: The History
of the electron as we know it(glue into to
notebook).
– There are extras on the table if you need one
– Fill in as much of it as you can.
– You should be able to answer several of them
– This should prepare you to begin today’s
lesson on the Quantum Model
• Grab a sheet that has the squares on it as
well (Glue into notebook).
Relationship between an Atom and Energy
• Ground State: The lowest energy state of an
atom.
• Excited State: The state in which an atom has
absorbed energy. The electrons are further away
from the nucleus.
• Quantum: The amount of energy needed to move
an electron from one energy level to the next.
(From Ground state to an Excited state)
• Photon: A particle of light that is carrying a
quantum of energy.
• Absorb- When an atom receives energy then it
Absorbs energy.
Bohr Model
• Emit- When an atom gives off energy then it is
emitting energy.
• Niels Bohr -developed a model of a hydrogen
atom that showed the electron circling the
nucleus in a fixed path.
– He determined that each energy level had a
particular amount of electrons that could occupy
each level. (fill in worksheet)
• 2 things wrong with Bohrs Model:
– It only worked for Hydrogen
• why?
– It didn’t explain the atoms bonding ability or
chemical behavior (video)
The Quantum Model
• Heisenberg Uncertainty Principle-It is
impossible to know both the position and
velocity of an electron at the same time.
– Mice and Cockroaches!!
• Quantum Model-Model that shows the
location of all electrons in an atom
• Orbitals- three dimensional region around
the nucleus that indicates the probable
location of an electron.
– 90% of the time
Quantum Numbers
• Quantum Numbers- 4 numbers used to tell
us where an electron is located in an atom
1. Principal Quantum Number (n)
2. Angular Momentum Quantum Number ( l )
3. Magnetic Quantum Number
4. Spin Quantum Number
Quantum Numbers
• Pauli Exclusion Principle: no two electrons
in the same atom can have the same set of
quantum #s.
1-Principal Quantum #
• Tells us which energy level an electron is in
• Symbolized by n
• Can have a value of 1,2,3,4,5,6,or 7
– Example n=3 means the electron is in the 3rd
energy level.
2-Angular Momentum Quantum #
• Gives the shape of the orbital the
electrons are making
• Symbolized by ( l )
• ( l ) can have a value of s, p, d, or f
#2-Angular Momentum
s Orbital
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s can have only ONE part
spherical or round shape (like a ball)
Can hold 2 electrons total
Lowest in energy
Periodic table Groups 1-2
SubOrbitals
• Some of the Orbital shapes have parts
• Each part can hold only TWO electrons
each.
#2-Angular Momentum
p Orbital
• p orbital can have THREE orientations
-orientated on the x axis
-orientated on the y axis
-orientated on the z axis
• dumbbell shaped
• Each dumbell can hold 2 e• 3 different orientations account for the total of 6
electrons in the p Orbital ( 3 x 2=6)
• Periodic table Groups 13-18
• Second lowest in energy
#2-Angular Momentum
d Orbital
• 5 different orientations
• Each d shape can hold 2 e• 5 different orientations account for the 10
possible electrons (5x2=10)
• d sublevels are described as being lobed
• Periodic table groups 3-12
• Third in energy
#2-Angular Momentum
f Orbital
• f sublevels can have 7 orientations
• Each shape can hold 2 e• resulting in a maximum of 14 electrons in
the f orbital ( 7 x 2=14)
• Shape not important
• Periodic table groups: Lanthanides and
Actinides (the two rows at the bottom)
• Highest in energy
#2-Angular Momentum
s Orbital
• s sublevel can have only ONE orientation
or part
• spherical or round shape (like a ball)
• Can hold 2 electrons total
• Periodic table Groups 1-2
• Lowest in energy
3-Magnetic Quantum #
• Tells us which plane or axis the orbital is in
4-Spin Quantum #
• Tells us if the electron is spinning
clockwise or counter-clockwise
Electron Configurations
• Shows the arrangement of electrons in
atoms (address or blueprint)
• In the neutral state each element has a
different electron configuration, b/c every
element has a different # of electrons.
Aufbau principle
• States that an electron occupies the
lowest-energy sublevel that can receive it.
• Electrons take the path of least
resistance..Lazy Electrons
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How to know where electrons fill?
• Electrons always fill lowest energy level
first (1,2,3,4,5,6,7)
• Electrons fill lowest orbital in each energy
level first (s,p,d,f)
Representing Electron
Configurations
Four ways to show arrangement of electrons
1. Electron Configuration Notation(long)
2. Noble Gas Configuration(short cut)
3. Orbital Notation(arrows)
4. Electron Dot Notation(dots)
1-Electron Configuration Notation
• Shows all electrons in atom
• Gives
– Energy Level
– Shape of Orbital
– Number of electrons in each orbital
• Example: Hydrogen
1S1
# of electrons
Orbital Type
Main Energy Level
How to write electron
configurations
• Always start with 1s
• Continue to fill orbitals as needed
• When you have to jump to the next energy
level, ALWAYS start back filling in the s
orbital.
• Remember that all energy levels have an s
orbital.
Electron Configuration-period two
elements
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H
He
Li
Be
B
C
N
O
F
Ne
1s1
1s2
1s22s1
1s22s2
1s22s22p1
1s22s22p2
1s22s22p3
1s22s22p4
1s22s22p5
1s22s22p6
Electron Configurations-period
three elements
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Na
Mg
Al
Si
P
S
Cl
Ar
1s22s22p63s1
1s22s22p63s2
1s22s22p63s23p1
1s22s22p63s23p2
1s22s22p63s23p3
1s22s22p63s23p4
1s22s22p63s23p5
1s22s22p63s23p6
Fourth period elements
• So far, electrons have filled in a
predictable order.
• This changes in the fourth period.
• 4s will fill before 3d, because 4s has less
energy than 3d. (electrons always take
path that uses less energy)
Fourth period elements
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K
Ca
Sc
Ti
Zn
Ga
Ge
As
Se
Br
Kr
1s22s22p63s23p64s1
1s22s22p63s23p64s2
1s22s22p63s23p64s23d1
1s22s22p63s23p64s23d104p1
Exception to every rule
• There are some exceptions to the Aufbau
principal for elements 24 and 29
– Cr: 1s2 2s2 2p6 3s2 3p6 4s1 3d5
– Cu: 1s2 2s2 2p6 3s2 3p6 4s1 3d10
Elements of the fifth period
• Rb
• Sr
1s22s22p63s23p64s23d104p65s1
1s22s22p63s23p64s23d104p65s2
Write the electron configuration
notation for the following:
• 1. Boron (B)
• 2. Magnesium (Mg)
• 3. Argon (Ar)
• 4. Calcium (Ca)
• 5. Bromine (Br)
Noble gas configurations
-A short hand way of writing an electron
configuration using noble gases.
-First, determine what period the element is in.
-Second, put the noble gas in the previous
period in [ ]. The noble gas in [ ]accounts
for its atomic # of electrons.
Noble gas configurations
• Compare the configuration of the noble gas Ne to all of
the period 3 elements. All period 3 elements start off
with Neon’s configuration
• Ne
1s22s22p6
• Na
1s22s22p63s1
• Mg
1s22s22p63s2
• Al
1s22s22p63s23p1
• Si
1s22s22p63s23p2
• P
1s22s22p63s23p3
• S
1s22s22p63s23p4
• Cl
1s22s22p63s23p5
• Ar
1s22s22p63s23p6
Noble gas configurations
• Third-start filling with the energy level that
equals the period #.
• Ex: write the noble gas configuration for
sodium, Na
– Na is in the 3rd period, so use the noble gas in
the 2nd period, which is Ne
– [Ne]3s1
Hund’s Rule
• States that each part of an orbital should
get 1 electron before any of the parts can
have 2.
• Don’t be stingy you have to share!!!
Orbital Notation
• Coincides with electron configuration
notation.
• Orbital notation is a diagram that shows
Hund’s rule.
Dot notation
• Shows only valence shell (outer) electrons
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Group 1 has 1 valence electron
Group 2 has 2 valence electrons
Group 13 has 3 valence electrons
Group 14 has 4 valence electrons
Group 15 has 5 valence electrons
Group 16 has 6 valence electrons
Group 17 has 7 valence electrons
Group 18 has 8 valence electrons
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Dot notation continued
• First-write the symbol of the element
• Second-determine the group of the
element and decide # of outer electrons
• Third- Place dots around the symbol to
represent electrons in the outer shell
Electron Arrangement Quiz
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Write the electron configuration for the following:
K
2. Cl
Mg
4. Ga
F
6. Be
• What element have the following configuration:
7. 1s22s22p63s23p64s23d6
8. 1s22s22p4
9. [Ar] 4s23d5
• Write the noble gas configuration for the following:
9. S
10. P
11. Cl
12. Zr
Electron Arrangement Quiz
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3.
5.
Write the electron configuration for the following:
Na
2. Cl
Mg
4. Al
Br
6. Li
• What element have the following configuration:
7. 1s22s22p63s23p3
8. 1s22s2
• Write the noble gas configuration for the following:
9. Sr 10. Si
11. Cl
12.Y