Chapter 5 Electrons in Atoms

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Chapter 5Electrons in Atoms
Different colors of light are associated with the
movement of electrons
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5.1 Models of the Atom

• Key Concepts
• What was inadequate about Rutherfords atomic
  model?
• What was the new assumption in the Bohr model of
  the atom?
• What does the quantum mechanical model determine
  about the electrons in an atom?
• How do sublevels of principal energy levels
  differ?

3

• Rutherford (1897)
• Electrons move around a
• nucleus made of protons and neutrons
• Could not explain the _______________ properties
  of elements
• Ex why do metals change colors when
• heated?

chemical
4

• Bohr (1913) proposed that
• electrons are found in specific
• paths, or _________, around a nucleus
• Each orbit has a __________ energy level
• Ex rungs of a ladder
• The higher an electron is on the
• ladder, the farther it is away from
• the nucleus

orbitals
fixed
5

• Quantum ? the amount of energy needed to move an
  electron from one energy level to another
• Moving up energy levels ____________ energy
• Moving down energy levels _______ energy
  (light)
• Energy levels are not equally spaced
• It takes less energy to
• move between higher rungs
• or energy levels than lower
• ones

absorb
emit
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• Bohrs model only worked for hydrogen
• De Broglie (1923) proposed that small particles,
  like electrons, have _____________ properties
• Schrodinger (1926) devised a mathematical
  calculation to describe the wave-like movement of
  electrons
• _________________________
• Determines the allowed energies an electron can
  have and how _________ it is to find the electron
  at various locations around the nucleus

wave-like
Quantum Mechanical Model
likely
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Movement of electron is similar to movement of a
propeller blade Blade may be anywhere in
the blurry region
Electron may be found anywhere within
the electron cloud
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• The energy levels in the quantum mechanical model
  are labeled by _____________________________ (n)
• n 1, 2, 3, 4, 5, 6
• Each principle energy level has sublevels that
  correspond to different cloud shapes, called
  _______________________

principle quantum numbers
Name Principle Quantum Number Symbol
n Represents energy levels Values any integer
1
atomic orbitals
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• 4 Different Atomic Orbitals
• S orbital _____________ (1)
• P orbitals __________________ (3)
• 3. D orbitals ____________________ (5)
• 4. F orbitals ___________________ (7)

spherical
dumbbells
four leaf clovers
Complex shapes
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Principle energy level Number of sublevels Type of sublevel
n 1 1 1s (1 orbital)
n 2 2 2s (1 orbital) 2p (3 orbital)
n 3 3 3s (1 orbital) 3p (3 orbitals) 3d (5 orbitals)
n 4 4 4s (1 orbital) 4p (3 orbitals) 4d (5 orbitals) 4f (7 orbitals)
Orbitals get bigger because they can hold
more electrons
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• Notice that n of sublevels and of different
  shapes
• The order of the shapes moves from lowest energy
  to highest energy (s, p, d, f)
• Example n 2 sublevel shapes s p
• Name the shape(s) be for the following
• n 1
• n 3
• n 4

s s, p, d s, p , d, f
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• Notice the number of orbitals per shape
• s 1 - d 5
• p 3 - f 7
• If n 3, then we will have 3 different shapes
  (s, p d)
• The s shape has 1 orbital available
• The p shape has 3 orbitals available
• And, the d shape has 5 orbitals available
• How many orbitals does the 3rd energy level have?

It has 9 orbitals
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• What is the relationship between n 3 and 9
  available orbitals?
• 9 32
• So, we can say that n2 of orbitals available
• We represent each orbital by listing the energy
  level followed by the orbital shape
• 1s
• n 1, orbital shape sphere
• 3d
• n 3, orbital shape clover

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• How many orbitals are in the 3s sublevel?
• Well, we know that n 3 and that the orbital
  shape s
• The 3rd energy level can have 9 total orbitals
  between s, p, dbut we are only looking the s
  orbital
• ? There is only 1 orbital in the 3s sublevel
• Each orbital available can hold 2 electrons
• s 1 orbital 2 electrons
• p 3 orbitals 6 electrons
• d 5 orbitals 10 electrons
• f 7 orbitals 14 electrons

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• So, when n 4, we can have
• s 1 orbital 2 electrons
• p 3 orbitals 6 electrons
• d 5 orbitals 10 electrons
• f 7 orbitals 14 electrons
• 32 total electrons 2n2

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• of electrons at each main level 2n2
• n 1 _____ electrons
• n 2 _____ electrons
• n 3 _____ electrons
• n 4 _____ electrons

2
8
18
32
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Key Answer 1

• What was inadequate about Rutherfords atomic
  model?

It did not explain the chemical properties of
elements
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Key Answer 2

• What was the new assumption in the Bohr model of
  the atom?

An electron is found only in specific orbits
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Key Answer 3

• What does the quantum mechanical model determine
  about the electrons in an atom?

The likelihood or probability of finding
electrons in various locations around the nucleus
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Key Answer 4

• How do sublevels of principal energy levels
  differ?

The sublevels are the different shapes of the
electron clouds
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5.2 Electron Arrangement in Atoms

• Key Concepts
• What are the three rules for writing the electron
  configurations of the elements?
• Why do actual electron configurations for some
  elements differ from those assigned using the
  aufbau principle?

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• Unstable arrangements become more stable by
  ____________ energy
• Does the rock formation in the picture look
  stable? _______
• What will it eventually do to become more stable?

losing
No
It will fall or rearrange
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• In an atom, _________ and the ___________
  interact to make the most stable arrangement
  possible
• The ways in which electrons are arranged around
  the nuclei of atoms are called __________
  ____________________

electrons
nucleus
electron
configurations
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• Three rules tell you how to find the electron
• configurations of atoms
• 1. ______________________
• 2. ______________________
• 3. ______________________

Aufbau Principle
Pauli Exclusion Principle
Hunds Rule
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• Aufbau Principle electrons occupy the orbitals
  of __________ energy first

lowest
Each box represents an orbital
Will electrons occupy the 2s orbital or the 2p
orbital first? __________
2s
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• What do the three boxes by 2p represent?
• Which is higher, 3d or 4s?

The three dumbbell orbitals px, py, pz
3d
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• Pauli Exclusion Principle an atomic orbital may
  ________ at most two electrons that have
  ____________ spins

hold
opposite
Counterclockwise
Clockwise
________________________
___________________
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• Hunds Rule electrons occupy orbitals of the
  same energy in a way that makes the number of
  electrons with the ______ spin direction as large
  as possible
• Orbitals in the same sublevel have ________
  energy levels
• They all must have electrons with the same spin
  first
• Practice Put three electrons into the 2p
  sublevel

same
equal
2p
x
y
z
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• Practice put four electrons into the 2p
  sublevel
• Put five electrons into the 2p sublevel

2p
x
y
z
2p
x
z
y
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• If an orbital only has one electron in its box,
  it is called ______________
• Ex How many unpaired electrons are in the
  following sublevel?

unpaired
4
3d
xy
xz
yz
x2-y2
z2
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• We use all three rules to write a shorthand
  method for showing the electron configurations of
  an atom
• It consists of
• The _____________ of the main energy levels
• The ____________ of the atomic orbital
• _____________ indicating the of electrons

Number (n)
letter
Superscript
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• Practice Hydrogen
• How many electrons does hydrogen have? ___

1
1s1
_______________
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• Practice Helium
• How many electrons does helium have? ____

2
1s2
_______________
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• Practice Lithium
• How many electrons does lithium have? ____

3
1s22s1
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• Practice Carbon
• How many electrons does carbon have? ____

6
1s22s22p2
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• Practice Sulfur
• How many electrons does sulfur have? ____

16
1s22s22p63s23p4
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• Practice Titanium
• How many electrons does titanium have? ____

22
1s22s22p63s23p64s23d2
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• LETS COLOR!!!

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H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba 57-71 Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra 89-103 Rf Db Sg Bh Hs Mt Ds Uuu Uub Uuq
--- s block
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H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba 57-71 Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra 89-103 Rf Db Sg Bh Hs Mt Ds Uuu Uub Uuq
--- s block --- p block
41
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba 57-71 Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra 89-103 Rf Db Sg Bh Hs Mt Ds Uuu Uub Uuq
--- s block --- p block --- d block
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• Exceptional Electron Configurations
• Some atoms do not follow the aufbau principle
• Ex Copper 29 electrons _________________
• Actually is
  __________________
• Ex Chromium 24 electrons_______________
• Actually is ________________

1s22s22p63s23p64s23d9
1s22s22p63s23p64s13d10
1s22s22p63s23p64s23d4
1s22s22p63s23p64s13d5
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• These atoms are trying to become more
  ______________ by having sublevels that are least
  ______ full.
• Filled and half-filled energy sublevels are more
  stable than partially-filled energy sublevels.

stable
half
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Key Answer 1

• What are the three rules for writing the electron
  configuration of elements?

Aufbau Principle Pauli Exclusion Principle Hunds
Rule
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Key Answer 2

• Why do the actual electron configurations for
  some elements differ from those assigned using
  the aufbau principle?

They are trying to become more stable
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• What is the basis for exceptions to the aufbau
  diagram?
• Filled and half-filled orbitals are more stable
  than partially filled orbitals

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5.3 Physics and the Quantum Mechanical Model

• Key Concepts
• How does quantum mechanics differ from classical
  mechanics?
• How are the wavelengths and frequency of light
  related?
• What causes atomic emission spectra?

48

• The quantum mechanical model grew out of the
  study of ___________, which also moves in
  ___________
• If all objects have a wavelike motion, why cant
  we see this for ordinary objects like baseballs
  or trains?
• Classical Mechanics describes the motion of
  __________ objects
• Quantum Mechanics describes the motion of
  ________________ particles and __________

light
waves
Mass has to be very small in order to detect
wavelength
large
subatomic
atoms
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• Complete Wave Cycle
• Starts at _________
• Moves to its ___________ point and __________
  point
• Returns to ___________

zero
highest
lowest
zero
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• Amplitude
• a waves _________ from ______ to the __________
• Wavelength (?)
• Distances between the _____________

zero
height
crest
crests
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• Frequency (v)
• Number of wave cycles to pass a certain point per
  unit of _________
• Unit ______________________
• (SI) ____________ or ______

time
Cycles per second
Hertz (Hz)
S-1 (1/s)
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• The product of wavelength (?) and frequency (v)
  always equals a constant (c), the
  ____________________
• c 2.998 x 108 m/s

Speed of light
? x v c
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• Wavelength (?) and frequency are ____________
  proportional
• What happens to frequency when wavelength
  decreases?

inversely
Frequency increases
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• Sample Problem 5.1
• Calculate the wavelength (?) of the yellow light
  emitted by the sodium lamp shown above if the
  frequency of the radiation is 5.10 x 1014 Hz.
• c ?v
• c ?
• v
• 2.998 x 108 m/s
• 5.10 x 1014/s

5.88 x 10-7 m
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• According to the wave model, light consists of
  ___________________ waves
• Electromagnetic radiation includes
• _____________________
• _____________________
• _____________________
• _____________________
• _____________________
• _____________________
• _____________________
• ______________________

electromagnetic
Radio waves
Radar
Microwaves
Infared
Visible light
Ultraviolet light
X - Rays
G amma rays
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• Which type of electromagnetic radiation has the
  lowest frequency?

Radio waves
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• The different frequencies of visible light can be
  seen when sunlight is passed through a ________

prism
ROYGBIV
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• What color in the visible spectrum has the
  highest wavelength?

Red
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• Atoms emit light when their electrons move from a
  __________ energy level to a _________ energy
  level
• Higher energy levels ________ state
• n 2, 3, 4, 5,
• Lowest energy level _________ state
• n 1

higher
lower
excited
ground
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• The frequencies of light emitted by each element
  that separate into distinct lines is called its
  ____________________________
• Unique to each element like a ______________

Atomic emission spectra
fingerprint
Each gas glows a different color
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Key Answer 1

• How are wavelength and frequency of light related?

They are inversely proportional
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Key Answer 2

• What causes atomic emission spectra?

Electrons of atoms moving from an excited state
to a lower state
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Key Answer 3

• How does quantum mechanics differ from classical
  mechanics?

Quantum mechanics small objects Classical
mechanics large objects