5. Intro to Chemistry
• Chemistry
• Basics of Atoms and Molecules
• Reading Assignments
• Text: AP Module 1 pages 1-20
• Homework Assignment
• Module 1 Study Guide Questions p 24 # 1 -14
Introduction (p 1)
• Atoms and Molecules (p 1)
• Atom - the smallest chemical unit of a matter - very
small
• - Contrast with a continuous view of matter
• - Quick review of history of idea of atoms.
• - As of 2007 117 different kind of atoms elements have
been observed as of 2007,
• -- 94 occur naturally on Earth.
• - Experiment 1.1 Atoms and Molecules (p 1)
• Molecules - Two or more atoms linked
together to form a substance with unique
properties. See figure 1.1 page 4.
Examples
• - H2, O2, O3, H2O, H2O2
• Elements - Element, are pure substance
that from form one type of atom that is
defined by its atomic number; that is, by
the number of protons in its nucleus. The
term is also used to refer to a pure
chemical substance composed of atoms
with the same number of protons.
• Compounds - molecule made up of more
than one type of atom that are chemically
bonded together. The have unique
properties that can not be broken down
physically.
• Mixtures - substances mixed together
physically but not chemically bonded.
Measurement and Units (p 7)
• Dimension is a measurable characteristic.
Dimensions are used to describe the state or conditions
of the physical world around us. Sometimes dimensions
are referred to as a physical quality. Some examples of
dimensions are length, mass, time, electric charge, area,
speed, force, and weight.
• Fundamental dimensions describe the basic
characteristics of the universe. Derived dimensions
describe more complex characteristics of the universe
that are made up of various combinations of fundamental
dimensions.
• A unit is an agreed upon standard for measuring a dimension. It
allows us to give a numerical value to a dimension. Sometimes
dimensions are referred to as a physical quantity. Some examples of
units are kilograms, feet, meters, seconds, minutes, square feet,
square meters, miles per hours, meters per second and pounds.
• For example, mass (m) is a dimension and kilogram (kg) is a unit.
Mass is the "measurable characteristic" being described by the
"standard" or "unit" kilogram. To describe a quality of mass properly
you need to have the number value and units such as 6 grams.
• PLEASE, ALWAYS REMEMBER that an answer is WRONG if the
units are incorrect.
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The Metric or Standard
International System of Units
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There are many systems of units used to describe dimensions. In science the standard of units is
called the International System of Units or SI system. This system is often called the metric
system because many of the SI units were derived from the metric system. Some examples of SI
units are kilograms, meters and seconds. The SI units are very logical in that they use prefixes
based upon powers of 10 to describe large and small quantities. One tenth (1/10) of a meter is a
decimeter and 1/100 of a meter is a centimeter. For example, a decameter is 10 meters; a
hectometer is 100 meters.
The other system of measurement we commonly use in the United States is called the English
system. It uses units such as pounds, feet, and seconds. Since we use both systems in this
country, we will use both in this course.
See table 1.1 Page 9.
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Mass Distance
Time
Volume
Weight Newton Slug Manipulation Units (p 10)
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See table 1.2
Table of Metric or SI Prefixes.
Converting Between United (p 11)
• Using the concept of multiplying by a form of "1" (P 12)
• Converting Between System (p 14)
• Again using the concept of multiplying by a form of "1" (P 14)
– Experiment 1.2 Cubits and Fingers (p 15)
• Concentration (p 17)
• The quantity of a substance in a certain volume (somewhat like
density)
• Experiment 1.3 Concentration (p 17)
The Forces in Creation Part 3 Basics of Atoms
• Reading Assignments
– Text: Module 13 pages 313 - 340
• Homework Assignment
– Module 13 Study Guide Questions p 339340 # 1 -20
Introduction (p 313)
• You have learned about two
fundamental forces (Gravitational and
Electromagnetic)
• Now we will learn about the other two
Strong and Weak Nuclear Forces
The Structure of an Atom (p313)
• Model: (See p 314) - A schematic description of a
system that accounts for it known properties,
• More general: Some working representation of real
systems
• Models are simplifications or idealizations of the real
thing
• Some types of models:
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- Parables
- Rules
- Diagrams or physical model like the globe
- Analogs
- Mathematical
- Computer
Atomic Models:
• All atomic models are mathematical models that can be represented
by a diagram. Here are some examples of atomic models:
• Pre atomic: Matter is continuous
• Greek: (Democritus 440 BC) - Matter is made up of discreet
fundamental particles that can't be divided. The also can only
combine in certain ratios - Law of definite composition. H20, H2O2
• Dalton: First Experimental Model 1770 - 1840. (see page 69)
• Elements consisted of tiny "indestructible" particles called atoms.
– Atoms of different elements have unique sizes and properties.
– The reason an element is pure is because all atoms of an element were
identical and that in particular they had the same mass. He also said that
the reason elements differed from one another was that atoms of each
element were different from one another; in particular, they had different
masses.
Dalton Model - Picture of Dalton's Theory of the atom
Thomson's Model (1890 - 1920)
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Discovery of the electron experimenting with cathode (negative electrode) rays
Rutherford Model (1880's - 1930)
• Discovery of the proton
Bohr Model
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Energy Levels - Orbits
Electron's can only exist at certain energy levels or quanta
Photon (packet of light energy)
Beginning of quantum theory which explains very small - remember theory of
gravity can not explain the very small
Bohr Model Refined - The Proton - Neutron Model
• Chadwick Discovery: The Neutron:
– Chadwick discovers the neutron as part of
the nuclease in 1932. Led to current
module which is still in use.
Sub Atomic Particles
• Nucleus: Proton Neutron - weigh about the same both about 1 amu Nutron sloghly heavier
• Electron: about 2000 times lighter than proton or
Neutron
• Quarks make up protons, and Neutrons
• Breakup of neutron into proton, electron and
antineutrino
• Go over Bohr Model on p 314
• Relative size of atom and parts - p 315 - electron size
baseball stadium - nuclus a marble
More on the Atom
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Atom 99.99% empty (p 316)
How do we "touch"
Interaction of electrons (p316)
Atomic number - number of protons dictates type of atom (p317)
• Mass number (AMU) = Sum of Protons and
Nuetrons (see figure 13.3 on page 318)
• Isotopes: Same number of protons - but
different number of neutrons - same type of
atom with a different atomic mass (mass
number) (Page 18-319)
Current Quantum Mechanical Models
• Current Quantum Mechanical Models (p
315 and page 323)
• Based upon the uncertainty principal
and probabilities
• Bohr Orbits versus orbital, electron
levels, or shells
• Orbit number and Electron capacity
• 1 = 2, 2 = 8, 3 = 18, 4 = 32, 5 = 50 (see
table p 324)
Atoms, Elements, Compounds
• An atom of one element can't be change to an atom on another
element.
• Good place to contrast this as a hypothesis with the alchemist
hypothesis of Dalton's time.
• Compounds are made of atoms of different elements combined
together.
• Compounds are pure substance because the atoms of different
elements are bonded to one another and are not easily
separated from one another.
• Compounds have constant composition because they contain
a fixed ratio of atoms and each atom has its own characteristic
weight, thus fixing the weight ratio of one element to the other.
• In addition he said that chemical reactions involved the
rearrangement of combinations of those atoms.
The Periodic Table (p 320)
• Elements (p 319 - A collection of atoms that have all the same
number of protons - made up of the same type of atoms.
• Modern Periodic Table (p 103)
• Mendelev's 1880's - based upon atomic mass - Dalton's Atomic
Model
• Mosely 1912 - based upon atomic number
• Parts of Periodic Table (p 321)
• Groups or Family - arranged in columns - have similar properties
because they have same number of valence electrons - similar
electron configuration (indicated by Roman numeral). Main group A
or transition metals B
• Periods or series are in rows
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Metals
Metalloids
Nonmetals
Lanthanide Series - Actinide Series and result if they weren't modified
in shape (p107)
Periodic Trends
• Predicating Electron Configurations
• Atomic and ionic radii
• Decrease in size as you move from left to right
(gets heavier)
• Increase in size as you move down a column
• Negative ions increase in size
• Positive ions decrease in size.
• Ionization Energy
– Energy needed to remove electron Increase left to
right
• Decrease for the heavier atoms (down columns)
• Constant for metals
• Unusual things three letter, parenthesis
recently discovered - rows that are
below,
• Draw C12 Bohr Model - see page 323
• Draw Al 27 atom (p 324)
The Strong Force (p 325)
• Very strong short range force that keep the nucleus
together P to P and N. (Note that as atoms get
heavier the number of neutrons exceed the number
of protons - provided more strong force to keep the
Proton from repelling.
• Exchange of the pion particle causes the strong
force
• Short lived particles - cause very strong forces - p
326
• A closer look at quarks - protons and neutrons made
up of three quarks where the exchange of particle
are called gluons
Radioactivity - the Weak Force (p
327)
• Radioactivity or radioactive decay Breakdown of an atom into teo
or more atoms plus energy and particles are given off
• Caused by a release of energy when the weak nuclear force is
released - similar to the EM force (now thought to be a different
form of the same thing - like ice, liq after and vapor)
• Radioactive isotope: Isotope of an atom that is radioactive - used in
medicine.
• Types of radioactive decay (Radioactivity)
• Beta decay - Neutron -> proton + electron (beta particle) energy
• Example U239(92P) -> NP239(93P)
• Alpha decay - 2N + 2 P (He nucluis leaves the atom) + energy
• Example Po 214 (84P) -> Pb 210 (82P) + alpha particle (He nucleus)
+E
• See Fig13.56 page 328
• Gamma decay -Nuclus gives of high energy called gamma ray
• Example (p 329) Th 239 Unstable -> Th 239 stable + gamma ray
(photon) both have 90 P and 139 N.
Dangers of Radioactivity (p 330)
• Like tiny bullets - penetrates below the skin
• Gamma light but fast - most damaging takes a lead shield to stop them
• Beta light - faster than alpha but slower than
gamma least damaging. - Thin metal stops
them
• Alpha slow but heavy = paper stop stem
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Rate of Radioactive Decay (p
332)
• Some radioactive elements undergo
radioactive decay quickly, some very slowly
• Half life is the time it takes for half of radio
active material to decay
• 10 gram of U239(92P) -> 5 gram of U239(92P)
= 5 grams of NP239(93P (see figu 13.6 page
333)
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Radioactive Dating (p334)
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Using the amount of radiaactive material in a substance to detrime age
based upon decay rates
Example C-14
C14 decay to C12
Half life is 5700 years
Assumption is that when organisms died it had a certain amount of
C14 in it so there fore we can tell when it died because it would stop
taking in C14 and it would have so much less C14 so if it stated out
with 10 grams of C14 and it now has 1 gram of C14 then it would be
50,000 years
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Problems with C14 - deductive part - assumption of how much C14
was in the organism to start no on really knows. Based upon
uniformatariansim - about value since 1945 have change - why?? What
does this tell us.
Wonder of Water
• Reading Assignments
• Text: Module 4 pages 81 - 104
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• Homework Assignment
• Module 4 Study Guide Questions p 104
# 1 - 14
Introduction (p 81)
• Wonder of water
• Look at its composition H2O - what would you think it would be
based upon its molecular weight?
• Why:
• Is it liquid at normal temperatures - needed for life
• What can it change phase - weather - keeping balance temp
• Why does it have such a high heat capacity for a simple
molecule
• why does it expand when it freezes
• Why can it hold more O2 when it gets colder 2
• Evidence of the God as a Creator of the universe and His Love
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The Composition of Water (p 81)
• Water is made up 2 H for every O atom H2O
• Discover through the process of Electrolysis
• Pass current through a substance (water)
breaks substance down
• Negative tem H gas (H slight positive)
Negative terminal O2 Gas
• Water give of H2 and O2 gas in a 2:1 ratio
• Experiment 4.1 The chemical composition of
water (page 81)
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Experimental Terminology
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• Experimental Error - Errors/mistakes
cause value to not be perfect
• Peer review - other scientist look at
results in Journal
• Example cold versus hot fusion.
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Chemical Formulas (p 85)
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• Using symbols to represent chemicals
(H2O)
• Where names come from - some Latin
ferrum so Fe for Iron.
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Water's Polarity (p 86)
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Look at figures 4.2 and 4.3
H end of the molecule is slightly positive
O end of molecule slightly negative
Polar Molecule: Water has polarity (+ and - ends) and is called a polar
molecule - most molecules have some polar qualities. Water has just
enough to give its special properties.
Non Polar Molecules: Some molecules are quite nonpolar like oil
which don't mix well with water.
What's the big deal it is just water - if you gave someone a great gift
and they scoffed at how would you feel. Some substance allow water
an oil to be soluble in both soap.
Experiment 4.2 Waters polarity (p 86) (also water oil and dish
detergent.
Water as a Solvent (p 90)
• Solution: when you dissolve a solid or liquid into a liquid to
form
• Solvent - A liquid substance capable of dissolving other
substances.
• Water called near universal solvent
• Solute - A substance that is dissolved in a solvent solid or
liquid
• Ionic compounds (e.g NaCl) - water dissolves well because they
are polar molecules. (see figure 4.5.
• Experiment 4.3: Solvents and Solutes (p 90)
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Hydrogen Bonding (p93)
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Weak bond of hydrogen on one molecule with Oxygen of another
molecule.
See Fig 4.6. (p 94)
Hydrogen bonds link molecules together (related to polar nature of
H2).
See special statement on water bottom of page 94
Gives water its special properties
- latent heat - Phase change
High heat capacity
Liquid when you would think it would be a gas
Why it forms a crystalline structure and explains when it freezes
Cohesiveness of water
Exp: Comparing solid water to solid butter (p 95)
Water's Cohesion (p 97)
• The tendency of water to stick together
• Causes surface tension
• Meniscus shape of water on a glass - in
nature xylem
• What it is hard to get all the water of
something as compared to alcohol which is
more nonpolar.
• Exp Water Cohesion (p 97)
• Exp The forces between Molecules (p99)
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Hard and Soft Water (p100)
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• Hardware has dissolved ions of Ca+ or
Mg+ in it.
• Does not soap up as easily
• Can soften water by replacing Ca+ with
Na+ - but it is not as healthy.
Division of Matter
• Matter
• Mixtures Pure Substances
• Heterogeneous Homogeneous
Elements
• Compounds
• Elements and Their Symbols –
see periodic table
Chemical Bonds:
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Sharing or “borrowing” outer shell – valence – electrons.
Follow rule of the octave
S - , P 8, D 8 and so on
Ionic bonds – borrowing electrons – not really consider a bond, but
an ionic attraction’note – electron with proton is intra-molecular
interactions
Intermolecular interaction Example Na+ ClCovalent Bonds - sharing of electrons – true bond – very strong
bonds
Intermolecular bond
Single Bond
Double Bond
Triple Bond
Vader Walls Bonds
• Vader Walls – Hydrogen Bonds –
weak interactions – not a true bonds
cases by
• permanent dipole–permanent dipole
forces
• permanent dipole–induced dipole
forces
• induced dipole-induced dipole
Molecules and Chemical
Compounds (AP p 134 – 136)
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Single atoms Monatomic: In physics and chemistry, monatomic is a combination of
the words "mono" and "atomic," and means "single atom." It is usually applied to
gases: a monatomic gas is one in which atoms are not bound to each other.
At standard temperature and pressure (STP), all of the noble gases are monatomic.
These are helium, neon, argon, krypton, xenon and radon. The heavier noble gases
can form compounds, but the lighter ones are unreactive. All elements will be
monatomic in the gas phase at sufficiently high temperatures.
Molecules: Molecules are formed when atoms linked together (AP 134 – 135)
Diatomic molecules are molecules composed only of two atoms, of either the same
or different chemical elements. The prefix di- means two in Greek. Common diatomic
molecules are hydrogen, nitrogen, oxygen, and carbon monoxide. Most elements
aside from the noble gases form diatomic molecules when heated, but high
temperatures - sometimes thousands of degrees - are often required.
Chemical compound: a substance consisting of two or more elements chemicallybonded together in a fixed proportion by mass. The basic unit (smallest unit that has
these properties) of a compound is the molecule.
Chemical Symbols and
Formulas of Compounds
• -- Use of subscript - goes with
prior symbol
• -- Use of coefficient - in front of
atom or compound
Chemical and Physical Properties
and changes (AP p 136 – 137)
• -- Physical properties can be observed or measured without
changing the composition of matter. Physical properties are used to
observe and describe matter. Physical properties include:
appearance, texture, color, odor, melting point, boiling point, density,
solubility, polarity, and many others.
• -- Chemical properties of matter describes its "potential" to
undergo some chemical change or reaction by virtue of its
composition. What elements, electrons, and bonding are present to
give the potential for chemical change. It is quite difficult to define a
chemical property without using the word "change". Eventually you
should be able to look at the formula of a compound and state some
chemical property.
Chemical and Physical
Changes
• -- Physical changes occur when objects undergo a change that
does not change their chemical nature. A physical change involves a
change in physical properties. Physical properties can be observed
without changing the type of matter. Physical changes are
reversible. Examples of physical properties include: texture, shape,
size, color, odor, volume, mass, weight, and density.
• -- Chemical changes are the changes in a substance through
chemical reactions. The chemical reactants form a new product with
equal mass.
• The following can indicate that a chemical change took place,
although this evidence is not conclusive:
– * Change of color (e.g., rusting of iron causes a change in color from silver to
reddish-brown).
– * Change in temperature or energy, such as the production (exothermic) or loss
(endothermic) of heat.
– * Change of form (burning paper) (this change is difficult to reverse).
– * An unexpected change in color
– * Light, heat, or sound is given off.
– * gasses formed, often appearing as bubbles.
– * Formation of precipitate (insoluble particles).
– * The decomposition of organic matter (rotting food)
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For example, placing a pot of water on a hot stove element causes a change in
temperature and gas to be released (water vapor) but a chemical change did not take
place. It was simply a physical change / change of state. An example could be a log
that is burning.
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A chemical reaction produces new substances by changing the way in which atoms
look. In a chemical reaction old bonds are broken and new bonds are formed
between different atoms. This breaking and forming of bonds takes place when
particles of the original materials collide with one another. An example of a chemical
change is fireworks.