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Chapter 5 Electrons in Atoms

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Chapter 5 Electrons in Atoms Different colors of light are associated with the movement of electrons LETS COLOR!!! LETS COLOR!!! Practice: Lithium How many electrons ... – PowerPoint PPT presentation

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Title: Chapter 5 Electrons in Atoms


1
Chapter 5Electrons in Atoms
Different colors of light are associated with the
movement of electrons
2
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
6
  • 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
7
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
8
  • 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
9
  • 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
10
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
11
  • 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
12
  • 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
13
  • 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

14
  • 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

15
  • 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

16
  • of electrons at each main level 2n2
  • n 1 _____ electrons
  • n 2 _____ electrons
  • n 3 _____ electrons
  • n 4 _____ electrons

2
8
18
32
17
Key Answer 1
  • What was inadequate about Rutherfords atomic
    model?

It did not explain the chemical properties of
elements
18
Key Answer 2
  • What was the new assumption in the Bohr model of
    the atom?

An electron is found only in specific orbits
19
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
20
Key Answer 4
  • How do sublevels of principal energy levels
    differ?

The sublevels are the different shapes of the
electron clouds
21
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?

22
  • 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
23
  • 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
24
  • Three rules tell you how to find the electron
  • configurations of atoms
  • 1. ______________________
  • 2. ______________________
  • 3. ______________________

Aufbau Principle
Pauli Exclusion Principle
Hunds Rule
25
  • 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
26
  • What do the three boxes by 2p represent?
  • Which is higher, 3d or 4s?

The three dumbbell orbitals px, py, pz
3d
27
  • Pauli Exclusion Principle an atomic orbital may
    ________ at most two electrons that have
    ____________ spins

hold
opposite
Counterclockwise
Clockwise
________________________
___________________
28
  • 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
29
  • Practice put four electrons into the 2p
    sublevel
  • Put five electrons into the 2p sublevel

2p
x
y
z
2p
x
z
y
30
  • 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
31
  • 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
32
  • Practice Hydrogen
  • How many electrons does hydrogen have? ___

1
1s1
_______________
33
  • Practice Helium
  • How many electrons does helium have? ____

2
1s2
_______________
34
  • Practice Lithium
  • How many electrons does lithium have? ____

3
1s22s1
35
  • Practice Carbon
  • How many electrons does carbon have? ____

6
1s22s22p2
36
  • Practice Sulfur
  • How many electrons does sulfur have? ____

16
1s22s22p63s23p4
37
  • Practice Titanium
  • How many electrons does titanium have? ____

22
1s22s22p63s23p64s23d2
38
  • LETS COLOR!!!

39
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
40
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
42
  • 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
43
  • 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
44
Key Answer 1
  • What are the three rules for writing the electron
    configuration of elements?

Aufbau Principle Pauli Exclusion Principle Hunds
Rule
45
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
46
  • What is the basis for exceptions to the aufbau
    diagram?
  • Filled and half-filled orbitals are more stable
    than partially filled orbitals

47
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
49
  • Complete Wave Cycle
  • Starts at _________
  • Moves to its ___________ point and __________
    point
  • Returns to ___________

zero
highest
lowest
zero
50
  • Amplitude
  • a waves _________ from ______ to the __________
  • Wavelength (?)
  • Distances between the _____________

zero
height
crest
crests
51
  • 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)
52
  • 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
53
  • Wavelength (?) and frequency are ____________
    proportional
  • What happens to frequency when wavelength
    decreases?

inversely
Frequency increases
54
  • 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
55
  • 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
56
  • Which type of electromagnetic radiation has the
    lowest frequency?

Radio waves
57
  • The different frequencies of visible light can be
    seen when sunlight is passed through a ________

prism
ROYGBIV
58
  • What color in the visible spectrum has the
    highest wavelength?

Red
59
  • 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
60
  • 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
61
Key Answer 1
  • How are wavelength and frequency of light related?

They are inversely proportional
62
Key Answer 2
  • What causes atomic emission spectra?

Electrons of atoms moving from an excited state
to a lower state
63
Key Answer 3
  • How does quantum mechanics differ from classical
    mechanics?

Quantum mechanics small objects Classical
mechanics large objects
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