Transcript CHEM 5013 Applied Chemical Principles

CHEM 5013
Applied Chemical Principles
Chapters Six and Seven
Professor Bensley
Alfred State College
Chapter Objectives
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Describe and explain the relationship
between the wave and particle theories of
light and electrons.
Explain the true model of the atom using
atomic orbital nomenclature concepts.
Learn how to write electron configurations
for atoms and ions.
Chapter Objectives
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Explain the relationship between electron
configurations, valence electrons and the
Periodic Table.
Describe the various types of chemical
bonding (ionic and covalent) using valance
electron concepts and Lewis Structures.
Electromagnetic Spectrum
The Wave Nature of Light
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Light can be described by four variables.
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Wavelength, :
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Frequency, :

Velocity, c:
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Amplitude, A:
The Wave Nature of Light
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c = 
1 meter = 1 x 10
-9
nm
What is the wavelength of blue light with
a frequency of 6.4 x 1014 /s?
Check your answer – visible light is in the
range of roughly 380 to 750 nm
Quantum Effects and Photons
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What happens when you put metal in a
flame?
Atoms naturally vibrate with a defined
frequency depending on the solid
Absorption:
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Emission:
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Quantum Effects and Photons
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Photons:
E = h =
hc

Atomic Spectra
The blue-green line of the hydrogen
atom spectrum has a wavelength of
486 nm. What is the energy in one
photon of this light?
Fundamental Concepts of the
Atom

Electrons are
depicted as clouds
of negative charge
surrounding the
nucleus.
The
density of the
small dots is related to
the probability of
finding an electron at a
particular location.
Atomic Orbitals
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Location of an electron is described by 4
quantum numbers:
1.
2.
3.
4.

Think of them as addresses or locations:
 Streets
 Houses
 Rooms
Orbital Diagrams and Pauli Exclusion
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Orbital Diagrams:
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Electron spin represented by arrows (Spin Up, Spin Down)
Examples: Hydrogen, Helium, Lithium, Beryllium, Boron
Pauli Exclusion Principle
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No two electrons in an atom can have the same
four quantum numbers.
Pauli Exclusion Principle
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Which of the following electron configurations or
orbital diagrams are allowed and which are not
allowed by the Pauli Exclusion Principle? If it is
not allowed, explain why.
a) 1s22s12p3
b) 1s22s12p8
c) 1s22s22p63s23p63d8
d) 1s22s22p63s23p63d11
e) 1s 2s
Periodicity of Elements
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Period # gives outermost shell containing
electrons in ground state.
Group number gives the number of valence
electrons.
Write the electron configuration for Tellerium.
(Atomic number = 52)
How many valence electrons in an atom of
Tellerium in the ground state?
Building Up Principle
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Chemical properties of an element are primarily
related to ground state electron configuration.
Example (1st 11 elements)
Do you see a pattern? This can be explained by
the building up principle (Aufbau Principle)
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This order of subshells corresponds to increasing
energy levels of the subshells

We fill orbitals starting with lowest energy(1s) and
proceed to highest energy (building up)
Questions?
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So what happens when you get to Carbon?
Hund’s Rule:
What is the electron configuration for the
ground state of sulfur?
Look at the Noble Gases (Ne, Ar, Kr, Xe) – they
are chemically inert. Why?
Shorthand electron configuration:
Core vs. Valence Electrons
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Two types of electrons represented in
shorthand electron configuration:
1.
Core electrons:
2.
Valence electrons:
Write the shorthand electronic configuration
for Sulfur.
So, how many valence electrons are there
in Sulfur?
Chemical Bonding - Video
REVIEW – What is an ion?
 Ionic Bonds:
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Example: NaCl
Na =
+
Cl =
__ valence electrons?
__ valence electrons?
What happens to the valence electrons?
FORMS

Ionic Bonds
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You can simplify the equation using Lewis
Electron-Dot Symbols
Use Lewis Dot Symbols to represent the
transfer of electrons in forming Calcium
Oxide, CaO, from atoms.
•
Ca
••
•
+
•
O
•
•
•
••
2+
•
•
Ca + • O •
••
2-
Lewis Symbol Examples
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Use Lewis symbols to represent the
formation of Calcium Chloride.
Write the electron configuration and
Lewis symbol for Ca 2+
Write the electron configuration and
Lewis symbol for S 2-
Covalent Bonds
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Covalent Bonds:
Consider H2:
H
•
•
H
Or HCl:
:
Cl:
:
•
•
H
Lewis Dot Formulas
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Definition:
: :
: :
Bonding Pair
H Cl
Lone Pair
Octet Rule – Covalent Compounds
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Atoms in covalent compounds obtain
noble gas configurations by sharing
electrons.
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Octet Rule:
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Exception:
Multiple Bonds
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Double Bonds
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Definition:
Example: Carbon dioxide CO2
Triple Bonds
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Definition:
Example: Acetylene C2H2
Lewis Structure Examples
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Write the Lewis Structures for the
following:
1.
2.
3.
OF2
H2O
Carbon monoxide