Title: Chemistry: Matter and Change
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2Chapter Menu
Electrons in Atoms
Section 5.1 Light and Quantized Energy Section
5.2 Quantum Theory and the Atom Section 5.3
Electron Configuration
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3Section 5-1
Section 5.1 Light and Quantized Energy
- Compare the wave and particle natures of light.
- Define a quantum of energy, and explain how it is
related to an energy change of matter. - Contrast continuous electromagnetic spectra and
atomic emission spectra.
radiation the rays and particles alpha
particles, beta particles, and gamma raysthat
are emitted by radioactive material
4Section 5-1
Section 5.1 Light and Quantized Energy (cont.)
electromagnetic radiation wavelength frequency amp
litude electromagnetic spectrum
quantum Planck's constant photoelectric
effect photon atomic emission spectrum
Light, a form of electromagnetic radiation, has
characteristics of both a wave and a particle.
5Section 5-1
The Atom and Unanswered Questions
- In Rutherford's model, the atoms mass is
concentrated in the nucleus and electrons move
around it.
- The model doesnt explain how the electrons were
arranged around the nucleus. - The model doesnt explain why negatively charged
electrons arent pulled into the positively
charged nucleus.
6Section 5-1
The Atom and Unanswered Questions (cont.)
- In the early 1900s, scientists observed certain
elements emitted visible light when heated in a
flame.
- Analysis of the emitted light revealed that an
elements chemical behavior is related to the
arrangement of the electrons in its atoms.
7Section 5-1
The Wave Nature of Light
- Visible light is a type of electromagnetic
radiation, a form of energy that exhibits
wave-like behavior as it travels through space.
- All waves can be described by several
characteristics.
8Section 5-1
The Wave Nature of Light (cont.)
- The wavelength is distance from crest to crest or
from trough to trough.
- The frequency is the number of waves that pass a
given point per second. - The amplitude is the waves height from the
origin to a crest.
9Section 5-1
The Wave Nature of Light (cont.)
10Section 5-1
The Wave Nature of Light (cont.)
- What relationship do you see between
?, v, and c? - All waves move at the same speed!!!
11Section 5-1
The Wave Nature of Light (cont.)
- Frequency and wavelength have an inverse
relationship!!!
12Section 5-1
The Wave Nature of Light (cont.)
- Sunlight, or visible light, contains a continuous
range of wavelengths and frequencies.
- A prism separates sunlight into a continuous
spectrum of colors pg. 138. - The electromagnetic spectrum includes all forms
of electromagnetic radiation pg. 139.
13Section 5-1
The Wave Nature of Light (cont.)
14- The Wave Nature of Light (cont.)
15- The Wave Nature of Light (cont.)
Note the trends Blue light has shorter ?, higher
v, and more energy. Red light has longer ?,
lower v, and less energy. http//www.brainpop.co
m/science/energy/electromagneticspectrum/
16Section 5-1
The Particle Nature of Light
- The wave model of light cannot explain all of
lights characteristics.
- Quantum as the minimum amount of energy that can
be gained or lost by an atom.
17Section 5-1
The Particle Nature of Light (cont.)
- The wave theory could also not explain the
photoelectric effect - electrons are emitted from
a metals surface when light of a certain
frequency shines on it (how solar calculators
work).
- http//phet.colorado.edu/en/simulation/photoelectr
ic
18Section 5-1
The Particle Nature of Light (cont.)
- Albert Einstein proposed in 1905 that light has a
dual nature.
- Einstein suggested light can have wave and
particle properties. - A photon is a particle of electromagnetic
radiation with no mass that carries a quantum of
energy. - As frequency increases, the energy of the wave
also increases!
19Section 5-1
Atomic Emission Spectra
- Light in a neon sign is produced when electricity
is passed through a tube filled with neon gas and
excites the neon atoms.
- The excited atoms emit light to release energy.
20Section 5-1
Atomic Emission Spectra (cont.)
21Section 5-1
Atomic Emission Spectra (cont.)
- The atomic emission spectrum of an element is the
set of frequencies of the electromagnetic waves
emitted by the atoms of the element.
- Each elements atomic emission spectrum is unique
they have their own fingerprints!
22Section 5-1
Section 5.1 Assessment
What is the smallest amount of energy that can be
gained or lost by an atom? A. electromagnetic
photon B. beta particle C. quanta
D. wave-particle
- A
- B
- C
- D
23Section 5-1
Section 5.1 Assessment
What is a particle of electromagnetic radiation
with no mass called? A. beta particle B. alpha
particle C. quanta D. photon
- A
- B
- C
- D
24End of Section 5-1
25Section 5-2
Section 5.2 Quantum Theory and the Atom
- Compare the Bohr and quantum mechanical models of
the atom.
- Explain the impact of de Broglie's wave article
duality and the Heisenberg uncertainty principle
on the current view of electrons in atoms. - Identify the relationships among a hydrogen
atom's energy levels, sublevels, and atomic
orbitals.
atom the smallest particle of an element that
retains all the properties of that element, is
composed of electrons, protons, and neutrons.
26Section 5-2
Section 5.2 Quantum Theory and the Atom (cont.)
ground state quantum number de Broglie
equation Heisenberg uncertainty principle
quantum mechanical model of the atom atomic
orbital principal quantum number principal energy
level energy sublevel
Wavelike properties of electrons help relate
atomic emission spectra, energy states of atoms,
and atomic orbitals.
27Section 5-2
Bohr's Model of the Atom
- Bohr correctly predicted the frequency lines in
hydrogens atomic emission spectrum.
- The lowest allowable energy state of an atom is
called its ground state. - When an atom gains energy, it is in an excited
state.
28Section 5-2
Bohr's Model of the Atom (cont.)
- Bohr suggested that an electron moves around the
nucleus only in certain allowed circular orbits -
Planetary Atomic Model.
29Section 5-2
Bohr's Model of the Atom (cont.)
- Each orbit was given a number, called the quantum
number.
30Section 5-2
Bohr's Model of the Atom (cont.)
- When electrons gain energy, they can move from
the ground state to an excited state.
- http//www.visionlearning.com/img/app/library/obje
cts/Flash/VLObject-1347-070828110836.swf
31Section 5-2
Bohr's Model of the Atom (cont.)
32Section 5-2
Bohr's Model of the Atom (cont.)
- Bohrs model only worked for hydrogen, but not
for all of the other elements.
- The behavior of electrons is still not fully
understood, but it is known they do not move
around the nucleus in circular orbits.
33Section 5-2
The Quantum Mechanical Model of the Atom
- Louis de Broglie (18921987) hypothesized that
particles, including electrons, could also have
wavelike behaviors.
34Section 5-2
The Quantum Mechanical Model of the Atom (cont.)
- Heisenberg showed it is impossible to take any
measurement of an object without disturbing it.
35Section 5-2
The Quantum Mechanical Model of the Atom (cont.)
- The Heisenberg uncertainty principle states that
it is fundamentally impossible to know precisely
both the velocity and position of a particle at
the same time. - The only quantity that can be known is the
probability for an electron to occupy a certain
region around the nucleus.
36Section 5-2
The Quantum Mechanical Model of the Atom (cont.)
- Schrödinger treated electrons as waves in a model
called the quantum mechanical model of the atom
(electron cloud model).
- Schrödingers equation applied equally well to
elements other than hydrogen!!!
37Section 5-2
The Quantum Mechanical Model of the Atom (cont.)
- We now understand that atoms have a spherical
shape where the nucleus is surrounded by the
electron cloud.
38Section 5-2
Section 5.2 Assessment
Which atomic suborbitals have a dumbbell shape?
A. s B. f C. p D. d
- A
- B
- C
- D
39Section 5-2
Section 5.2 Assessment
Who proposed that particles could also exhibit
wavelike behaviors? A. Bohr B. Einstein
C. Rutherford D. de Broglie
- A
- B
- C
- D
40End of Section 5-2
41Section 5-3
Section 5.3 Electron Configuration
- Apply the Pauli exclusion principle, the aufbau
principle, and Hund's rule to write electron
configurations using orbital diagrams and
electron configuration notation.
- Define valence electrons, and draw electron-dot
structures representing an atom's valence
electrons.
electron a negatively charged, fast-moving
particle with an extremely small mass that is
found in all forms of matter and moves through
the empty space surrounding an atom's nucleus
42Section 5-3
Section 5.3 Electron Configuration (cont.)
valence electrons electron-dot structure
Electrons are arranged in energy levels in the
electron cloud.
43Section 5-3
Ground-State Electron Configuration
- In a neutral atom, the number of protons equals
the number of electrons. - These electrons are arranged in energy levels
around the nucleus.
44Section 5-3
Ground-State Electron Configuration
- Energy increases as levels move away from the
nucleus. - Electrons must fill the lower energy levels, then
move to higher energy levels.
45Section 5-3
Ground-State Electron Configuration (cont.)
- Maximum number of e- in each energy level
- Level 1 maximum of 2 e-
- Level 2 maximum of 8 e-
- Level 3 maximum of 18 e-
- Level 4 maximum of 32 e-
- Level 5 maximum of 50 e-
46Section 5-3
Ground-State Electron Configuration (cont.)
- In energy level 3 and higher, several additional
electrons can be added to inner sublevels. - This leaves the outer level with a maximum of
only 8 e-. - These are called valence electrons!
47Section 5-3
Valence Electrons
- Valence electrons are defined as electrons in the
atoms outer energy level.
48Section 5-3
Valence Electrons
- An elements valence electrons determine the
chemical properties of the element.
- Electron-dot structure consists of the elements
symbol representing the nucleus and inner
electrons, surrounded by dots representing the
elements valence electrons.
49Section 5-3
Section 5.3 Assessment
In the ground state, which orbital does an atoms
electrons occupy? A. the highest
available B. the lowest available C. the n 0
orbital D. the d suborbital
- A
- B
- C
- D
50Section 5-3
Section 5.3 Assessment
The outermost electrons of an atom are called
what? A. suborbitals B. orbitals C. ground
state electrons D. valence electrons
- A
- B
- C
- D
51End of Section 5-3
52Resources Menu
Chemistry Online Study Guide Chapter
Assessment Standardized Test Practice Image
Bank Concepts in Motion
53Study Guide 1
Section 5.1 Light and Quantized Energy
Key Concepts
- All waves are defined by their wavelengths,
frequencies, amplitudes, and speeds. c ??
- In a vacuum, all electromagnetic waves travel at
the speed of light. - All electromagnetic waves have both wave and
particle properties. - Matter emits and absorbs energy in
quanta.Equantum h?
54Study Guide 1
Section 5.1 Light and Quantized Energy (cont.)
Key Concepts
- White light produces a continuous spectrum. An
elements emission spectrum consists of a series
of lines of individual colors.
55Study Guide 2
Section 5.2 Quantum Theory and the Atom
Key Concepts
- Bohrs atomic model attributes hydrogens
emission spectrum to electrons dropping from
higher-energy to lower-energy orbits. ?E E
higher-energy orbit - E lower-energy orbit E
photon h?
- The de Broglie equation relates a particles
wavelength to its mass, its velocity, and
Plancks constant. ? h / m? - The quantum mechanical model of the atom assumes
that electrons have wave properties. - Electrons occupy three-dimensional regions of
space called atomic orbitals.
56Study Guide 3
Section 5.3 Electron Configuration
Key Concepts
- The arrangement of electrons in an atom is called
the atoms electron configuration.
- Electron configurations are defined by the aufbau
principle, the Pauli exclusion principle, and
Hunds rule. - An elements valence electrons determine the
chemical properties of the element. - Electron configurations can be represented using
orbital diagrams, electron configuration
notation, and electron-dot structures.
57Chapter Assessment 1
The shortest distance from equivalent points on a
continuous wave is the A. frequency
B. wavelength C. amplitude D. crest
- A
- B
- C
- D
58Chapter Assessment 2
The energy of a wave increases as ____.
A. frequency decreases B. wavelength decreases
C. wavelength increases D. distance increases
- A
- B
- C
- D
59Chapter Assessment 3
Atoms move in circular orbits in which atomic
model? A. quantum mechanical model
B. Rutherfords model C. Bohrs model
D. plum-pudding model
- A
- B
- C
- D
60Chapter Assessment 4
It is impossible to know precisely both the
location and velocity of an electron at the same
time because A. the Pauli exclusion principle
B. the dual nature of light C. electrons travel
in waves D. the Heisenberg uncertainty
principle
- A
- B
- C
- D
61Chapter Assessment 5
How many valence electrons does neon have? A. 0
B. 1 C. 2 D. 3
- A
- B
- C
- D
62STP 1
Spherical orbitals belong to which sublevel?
A. s B. p C. d D. f
- A
- B
- C
- D
63STP 2
What is the maximum number of electrons the 1s
orbital can hold? A. 10 B. 2 C. 8 D. 1
- A
- B
- C
- D
64STP 3
In order for two electrons to occupy the same
orbital, they must A. have opposite charges
B. have opposite spins C. have the same spin
D. have the same spin and charge
- A
- B
- C
- D
65STP 4
How many valence electrons does boron contain?
A. 1 B. 2 C. 3 D. 5
- A
- B
- C
- D
66STP 5
What is a quantum? A. another name for an atom
B. the smallest amount of energy that can be
gained or lost by an atom C. the ground state
of an atom D. the excited state of an atom
- A
- B
- C
- D
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90CIM
Figure 5.11 Balmer Series Figure 5.12 Electron
Transitions Table 5.4 Electron Configurations
and Orbital Diagrams for Elements 110 Table 5.6
Electron Configurations and Dot Structures
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