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OME General Chemistry
Lecture 1: Introduction, Terms, Symbols
Dr. Hartwig Pohl
Office: Beyer-Bau 122e
Email: [email protected]
Phone: +49 351 463 42576
1
Course Schedule 2015
Week
Dates
Mon
Intro, Units, Charges,
Atom
Thurs
Bohr Model, Periodic
Table
1
Oct 19/22
2
Oct 26/29
no class
Ionic & Covalent Bonds
3
Nov 2/5
Hybridization
Reactions & Equations
4
Nov 9/12
Reactions & Equations
Review (Take Home Quiz)
5
Nov 16/19
Gas Laws
Kinetics
6
Nov 23/26
Thermodynamics
Electrochemistry
Review + Examples
7
Nov 30/Dec 3 Organic Molecules
8
Dec 7/10
9
Dec 14/17
Organic Molecules
Review & Questions
2
Course Summary
1. Introduction
1.1 Preface
1.2 What is Chemistry?
1.3 History of Chemistry
1.5 Units, constants, symbols
2. Atomic models and Periodic table
2.1 General terms
2.2 Size and mass of atoms
2.3 Subatomic particles
2.4 Distribution of elementary particles in the atom
2.5 Number of elementary particles in the atom
2.6 Composition of the atomic nucleus
2.7 Composition of the electron shell
2.8 Periodic table of elements
3
Course Summary (cont.)
3. Chemical bonds and chemical formulas
3.1 Properties of compositions with different types of bonds
3.2 Ionic bonds
3.3 Covalent bonds
3.4 Metal bond
3.5 Composition of solids
3.6 Chemical formulas
3.7 Amount of substance and stoichiometry
4. Reactions and equations
4.1 Driving force of reactions
4.2 Reaction equations
4.3 Stoichiometry
4.4 Reactions of inorganic chemistry
4
Course Summary (cont.)
5. Gases
5.1 Gas law
5.2 Partial pressure
5.3 Real gases
5.4 Condensation of gases
6. Kinetics and Reaction mechanism
6.1 Kinetics and stability of chemical compounds
6.2 Definition of reaction rate
6.3 Reaction: 2. order
6.4 Reaction: 1. order
6.5 Reaction mechanism
6.6 Temperature dependence of reaction rate constant
6.7 Catalysis
5
Course Summary (cont.)
7. Thermodynamics
7.1 Equilibrium and mass action law
7.1.1 Temperature dependence of the equilibrium
7.1.2 Principle of the smallest constraint
7.2 Measurement of heat
7.3 Reaction enthalpy and entropy/ driving force of reactions
8. Electrochemistry
8.1 Conductivity and electrolysis
8.2 EMF
9. Organic Molecules
Organic Chemistry (Dec 2015-Feb 2016)
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Course Materials
Lecture Slides
note taking, reference
Text Books
L. Pauling
“General Chemistry” or “College Chemistry”
J.A. Campbell
“Chemistry, the Unending Frontier”
C.E. Mortimer
“Chemistry”
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What is Chemistry?
Chemistry
branch of science concerned with the substances of which
matter (all things around us) is composed, the
investigation of their properties and reactions, and the
use of such reactions to form new substances.
Properties
characteristic qualities that can be observed without
performing a chemical reaction
Reaction
process that converts a substances into other substances
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Fields of Chemistry
Analytical Chemistry
Inorganic Chemistry
Organic Chemistry
Physical Chemistry
Technical Chemistry
Theoretical Chemistry
Biochemistry
Atmospheric Chemistry
Nuclear Chemistry
Food Chemistry
Pharmaceutical Chemistry
Photochemistry
Polymer Chemistry
Radiation Chemistry
Macromol. Chemistry
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History of Chemistry
Prehistoric
fire, pottery, tanning leather, dying cloth
Ancient
first definition of the atom as the simplest unit of matter
Elements: fire, air, water, earth; properties: hot, cold, dry,
wet
3500 BC glass, perfume, beer, wine, copper (from Malachite) in Egypt
2500 BC tin, iron, bronze (mixture of copper/tin)
1500 BC term element used in China
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History of Chemistry
1500 BC dyeing of cloths
Indigo (India)
Alizarin (Egypt, Crete)
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History of Chemistry
Alchemy
up to ca. 1500 AD
driven largely by the desire to turn cheap metals into gold
and to discover the Elixir of Life
established a base for chemistry and periodic table
12
Fathers of Modern Chemistry
1600-1800
Dalton
(Manchester)
composition of
chemical cmpds,
term atom
Berzelius (Austria,
Stockholm)
terms element,
substance
Boyle (London)
“The Sceptical
Chymist” (1661)
collisions of particles
in motion, more than
4 elements,
encouraged
experimentation
Lavoisier (Paris)
conservation of
mass, chemical
nomenclature, first
chemistry textbook
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First Synthesis of Organic Cmpds
1824
Oxalic acid by Wöhler, Göttingen
uses: cleaning agent,
extracting/isolating
metals
Friedrich Wöhler
1826
Aniline from Indigo
Aniline is used in many modern dye synthesis
and enabled the initial development of the dye
industry. BASF = Badische Anilin- und SodaFabrik
1828
Urea by Wöhler
AgNCO + NH4Cl → (NH2)2CO + AgCl
first synthesis of a organic cmpd
from inorganic precursor, believed
only possible with living organisms
1840
Chemical fertilizer
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Modern Chemistry
1865
Kekulé (Bonn)
formula for benzene
1880
v. Baeyer (Leverkusen)
synthesis of indigo
1870
L. Meyer (Tübingen), Mendelejew
(Petersburg): Periodic system
1896
Becquerel (Paris)
Radioactivity
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Modern Chemistry
1905
Planck, Einstein (Berlin, Zürich): quantum theory
1906
1910
1912
Emil Fischer: studies on proteins
Haber-Bosch method for ammonia production
v. Laue (Berlin), Bragg (London), Debye, Scherrer (Berlin): use of X-rays
for structural analysis
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Modern Chemistry
1913
Bohr (Kopenhagen), Rutherford (Manchester): Atomic model
1939
1953
1960
Hahn, Strassmann (Berlin): nuclear fission (not really chemistry)
Eigen (Göttingen): studies on very fast reactions t < 10–9 s
Woodward, Fischer: Synthesis of complex natural materials, including
chlorophyll, hemin, strychnine
Calvin: mechanism of photosynthesis
1961
...
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Further Advancements
• improvement and simplification of spectroscopic methods for analysis:
UV, IR, NMR, X-ray
• important findings in biochemistry: biochemical mechanisms
• synthesis of peptides, crystallization and X-ray structures of proteins
• functional polymers → modern plastics
• surface analysis: scanning electron microscopy (SEM), atomic force
microscopy (AFM) → resolution down to single atoms → surface analysis
→ catalysis; nanotechnology, Fullerenes
• environmental protection, solar energy
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Why Study Chemistry in OME?
“It is through chemistry and her sister sciences that the power of man, of
mind, over matter is obtained.”
- Pauling
Organic and Molecular Electronics (OME) Perspective
Understand…
• basic structure-property relationships and how they relate to
functions in the device
• how to tune device properties based on molecular structure and
engineering
• communicate effectively with colleagues
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Matter & Radiant Energy
The universe is composed of matter and radiant energy
Matter
all materials around us – gases, liquids, solids
Radiant Energy
light, x-rays, radio waves; ex: color of an object related to
its absorption of light
Chemistry is primarily concerned with the properties or characteristic
qualities of matter rather than the particular object itself.
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Types of Matter… Getting Specific
Objects
Heterogeneous
Materials
mixture… consists of
parts with different
properties; ex: granite
Homogeneous
Materials
same properties throughout
ex: quartz crystals
Pure
Substances
Solutions
homogeneous material
with definite composition
homogeneous mixture
ex: sugar in water
Elementary
Substances
substance that cannot
be decomposed
Compounds
substance that can be
decomposed into two or
more other substances
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Properties of Substances
Properties
characteristic qualities
Physical Properties
properties of a substance that can be observed
without changing the substance into other
substances
ex: taste, solubility, density, melting point,
malleability, ductility, hardness, color
Chemical Properties
properties that relate to its participation in
chemical reactions
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Energy Terms in Chemistry
Energy
involved in doing work or in heating an object; potential
energy, kinetic energy, heat, radiant energy
Chemical Energy energy from a chemical reaction which can do work; ex:
mixture of gasoline vapor and air ignites, energy is
liberated that can do the work of propelling a car, causes
an increase in temperature of the engine and the exhaust
gases
Law of the Conservation of Energy
whenever energy of one form disappears, an equivalent
amount of energy in another form is produced
Heat of the Reaction
difference in heat contents of the products and the
reactants
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Units & Symbols
SI-System (SI = Système international d´unités)
Length
Current
Mass
Temperature
Time
Amount
m
A
kg
K... (ºC)
s
mol
Derived units, e.g.
Force
N = kg m/s2
Specific to Chemistry…
Mass
g
Amount
mol
Molecular Weight
g / mol
Volume
mL
Solubility
g / mL
Density
g / cm3 = g / mL
Melting point
ºC
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Examples: Density
A piece of gold (Mass
= 301g) has a volume
of 15.6 cm3. Calculate
the density of gold.
The density of mercury,
the only liquid metal at
room temperature,
equals 13.6 g/cm3.
Determine the volume
of 5.50 g mercury.
density = mass / volume
density = mass / volume
density = 301 g / 15.6 cm3
volume = mass / density
density = 319.3 g / cm3
volume = 5.50 g / 13.6 (g/cm3)
volume = 0.404 cm3
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Example: Unit Conversion
The density of gold is 19,300 kg m-3. Calculate the density in g cm-3.
Density =
Density =
Density =
Density =
Density =
19.300 kg
1 m3
19.300 kg
1 m3
19.300 kg
1000 g
1 m3
1 kg
106 cm3
1000 g
1 m3
1 m3
1 kg
106 cm3
19.300
103 g
1
1
1
106 cm3
19.300
1g
1
103 cm3
= 19,3 g cm-3
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1.5 values of basic constants, units and symbols
Unit of atomic mass*
u = L-1 g/mol = NA-1 g/mol = 1,6605655 × 10-27 kg
Avogadro constant*
NA = 6,022045 × 1023 mol-1 (= Loschmidt-number L)
Bohr-Magneton
B = eh/(4me) = 9,274078 × 10-24 J/Tesla
Boltzmann constant*
kB = 1,380662 × 10-23 J/K
Electric constant
0 = 8,85418782 × 10-12 A2s2/(Jm)
Electron mass
me = 9,109534 × 10-31 kg
Elementary charge*
e = 1,6021892 × 10-19 As = 1,6021892 × 10-19 C
Apparent gravity
g = 9,81 m/s2 (average value)
Faraday constant*
FF = L × e = 96484,56 As/mol
Gas constant*
R = L × kB = 8,314472 J/(mol K)
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Gravity constant
G = 6,6720 × 10-11 m3/(kgs2)
Core Magneton
K = eh/(4mp) = 5,050824 × 10-27 J/Tesla
Speed of light*
c = 2,99792458 × 108 m/s (in vacuum)
Magnetic constant
0 = 4 × 10-7 Vs/(Am)
Planck constant*
h = 6,626176 × 10-34 Js
Proton mass
mp = 1,6726485 × 10-27 kg
* Particularly important for general chemistry
Not all of these constants are needed for this lecture. Usually, calculation to 4-5
decimals is sufficient.
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Letter
capital_lower case
A
a
B
b
G
g
D
d
E

Z
z
H
h
Θ
θ
I
i
K
k
Λ
λ
Μ
μ
Ν
v
X
x
O
o
P

R
R
Σ
σ,ς*
T
τ
Υ
υ
Φ
n
Χ
χ
Ψ
ψ
Ω
ω
*as final sound
Name
Alpha
Beta
Gamma
Delta
Epsilon
Zeta
Eta
Theta
Iota
Kappa
Lambda
My
Ny
Xi
Omikron
Pi
Rho
Sigma
Tau
Ypsilon
Phi
Chi
Psi
Omega
Pronounciation
old greek
new greek
a
a
b
w
g
g
d
th (soft)
e
e
ds
ds
ä
i
t (th)
th (hard)
i
i
k
k
l
l
m
m
n
n
ks
ks
o
o
p
p
r
r
s
s
t
t
ü
i
f
f
ch
ch
ps
ps
oh
oh
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OME General Chemistry
Lecture 2: Atomic Models & Periodic Table
Dr. Hartwig Pohl
Office: Beyer-Bau 122e
Email: [email protected]
Phone: +49 351 463 42576
30
The Atomic Theory
John Dalton (1805, Manchester)
All substances consist of small particles of matter, of several
different kinds, corresponding to the different elements
Atom
Molecule
smallest indivisible unit of an element
atomos (Greek) = indivisible
a group of atoms bonded to one another
Arguments in Support of the Theory:
•
•
•
Democritus (460-370 BC) shared similar definition of atom with
much less scientific backing
Lavoisier and the demonstration of conservation of mass during
a reaction
Constant proportions: different samples of a substance contain
its elements in the same proportions
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Size & Mass of Atoms
Modern microscopy methods enable to view atomic dimensions
(scanning tunneling- or atomic force microscopy (STM or AFM)).
Silicon
Graphite
Of course, it has been tried to further divide those particles, e.g. by collision with
other particles or by irradiation with high energies. In all cases, it has been found that
further division changes the properties.
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Size & Mass of Atoms
Pictures taken by scanning tunneling microscopy
Nickel atoms on a copper
surface
A ring of cobalt atoms
on a copper surface
The size of atoms can in principle be taken from the pictures above. However,
there are methods that are more precise and more simple, e.g. X-ray diffraction
–→ Distances are in the order of 100–200 pm in case of atoms.
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Size & Mass of Atoms
Molecules are accordingly larger, usually a few hundred to a few thousand pm,
some extremely large organic molecules may be even bigger.
Mass of atoms and molecules
Weighing is not possible due to small overall mass, but the methods described
above help; e.g. 1 cm3 of an element
X-ray diffraction → distances of atoms
→ number of atoms in 1 cm3,
→ mass of this number of atoms (Density )
→ mass of an atom (Caution: different lattice types)
Ex: Aluminum 4,489 × 10–23 g, Gold 3,27 × 10–22 g.
Molecules can be accordingly heavier, but calculation with such small numbers
is uncomfortable... atomic mass units
u: 1 u = 1,6605655 × 10–24 g
Ex: In this unit, the mass of an Aluminum atom is 26.89 u.
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Subatomic Particles - Electrons
Discovery of Electrons
(Stoney) substances can be decomposed by an electric current,
(Faraday) definite amount of electricity is needed to liberate a certain
amount of element from a compound
 electricity exists in discrete units
Properties of Electrons
particle with negative electric charge (units of electric charge =
Coulomb)
magnitude of charge, q = -1.602 x 10-19 C
mass, me = 9.107 x 10-28 g
 1/10,000 as large as an atom!
Flow of Electricity in a Metal
amount (coulomb)
rate (ampere = coulomb / second)
rate of flow dependent on… potential difference / voltage drop btw
ends
35
Subatomic Particles - Electrons
36
Determining the Charge of an Electron
How big is the charge of an electron? – Millikan 1906 Oil Drop Experiment
Spraying of oil droplets  velocity in presence of gravity noted, then charged
droplets were studied in the presence of a known electric field
q = –1,602 × 10–19 C (Coulomb) = –1,602 × 10–19 As
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Atomic Nuclei
Identification of a Nucleus (Rutherford)
every atom contains, in addition to one or more electrons, another
particle called the nucleus of the atom
every nucleus has a positive electric charge
very small, very heavy (compared to an electron)
nuclei are different for each element
Protons
simplest atomic nucleus
charge exactly equal and opposite to that of an electron (+1.601 x 10-19 C)
mass = mp = 1.672 x 10-24 g = 1836 x me = ca. 1 atomic mass unit
Neutrons
discovered by James Chadwick in 1932
mass = 1.675 x 10-24 g
no electric charge!
Nuclei are made up of protons and neutrons
38
Distribution of Particles in the Atom
If the foil is a few µm thick, most a-particles penetrate
through the foil without scattering.
Evaluation: electrons must be distributed around the outer portion of the atom.
Otherwise, far more particles must be scattered.
39
Distribution of Particles in the Atom
a) Expected result
b) Actual result
Rutherford deduced from that (and from other experiments) that an electron will not
diffract an a-particle from its track:
→ Matter consists mainly of empty space in which the point-shaped electrons move. The
atomic nucleus including protons and neutrons contains almost the whole mass.: 1/1836
and is extremely small.
40
Approximate Size of an Atom
The relative size of the nucleus with
respect to the atom is approximately the
same as a pea in the middle of this
stadium.
41
Number of Particles in the Atom
Larger amounts of matter must be neutral…
NUMBER OF PROTONS (PZ) = NUMBER OF ELECTRONS (EZ)
Each element has a particular number of protons. This is a definition of the term
element on an atomic basis:
Elements consist of atoms with an equal number of protons.
The chemistry of an element is a function of its number of electrons/protons…
Atomic number of the element (Z) = number of protons (= number of electrons)
Further classification by mass number (MZ) = number of neutrons + protons
number of protons = atomic number
number of electrons = atomic number (in case of neutral particles)
number of neutrons = mass number – atomic number (MZ – Z)
42
Number of Particles in the Atom
Number of protons
Number of electrons
Number of neutrons
Atomic number
Mass number
PZ = EZ
EZ = PZ
NZ = MZ – EZ
Z = PZ = EZ
MZ = PZ + NZ
Element Name Symbol
MZ
Z
EZ
PZ
NZ (MZ-Z)
Sodium
Na
23
11
11
11
12
Aluminum
Al
27
13
13
13
14
Gold
Au
197
79
79
79
118
43
Number of Neutrons: Isotopes
Most elements appear with a variety of masses, i.e. the atoms contain the same number
of protons but different numbers of neutrons. By suitable techniques, the atoms with
different neutron numbers can be separated. These different atom types are called
Isotopes. Isotopes are therefore elements with same numbers of protons but different
numbers of neutrons.
Most elements consist of a number of isotopes, sometimes mainly of one isotope, some
of complex mixtures.
e.g. hydrogen
99,99% MZ = 1 / 0,01 % MZ = 2
(Isotope with MZ = 2 has a name of its own = Deuterium)
Chlorine
Tin
75,5 % MZ = 35 / 24,5 % MZ = 37
Mixture of 10 Isotopes
Isotopes of an element do not differ with respect to their chemical properties.
44
Isotopes of Sodium
Two isotopes of Sodium:
23
11 Na
und
24
11 Na
45
Information from Periodic Table
46