1.1 (Matter in the Universe)

Matter in the universe is thought to have a common origin (come from the same
time and place.) This common origin is known as the Big Bang. Matter in the
universe is spreading out as evidenced by the red shift seen in distant galaxies. If
matter is spreading out through the universe today, then scientists logically
conclude that the matter must have started spreading out from a starting point
billions of years ago. This starting point is called the Big Bang.

Every element produces its own unique light spectrum. When astronomers study
the light from space they see the spectra for elements that we already have on
earth. They haven’t seen a new spectrum out there that we don’t already
recognize on earth. Therefore, we assume that the elements out there are the
same as the elements on earth.

On average, the universe is 74% hydrogen, 21% helium, 1% oxygen and less
than 1% everything else. As a general rule, the heavier and bigger the atoms, the
less of them we observe in the universe.

On earth, we don’t have much hydrogen or helium because earth doesn’t have
enough gravity to hold down these two lightest elements. Therefore, earth has a
greater % abundance of the heavier elements compared to the rest of the universe.
1.2 (Atoms)
Read about cathode ray tubes and the discoveries of Joseph John Thompson. (pages
72—73 of your text) What evidence led him to conclude that electrons are present in
atoms of all elements and that the electrons in one element are the same as the electrons
in another element? What evidence led him to conclude that electrons have a negative
charge?
Describe Thompson’s “Plum Pudding” model of an atom.
Read about the discovery of the atomic nucleus on page 74. What was so surprising
about the gold foil experiment? What evidence led Rutherford to conclude that the
nucleus of an atom is very small compared to the total volume of an atom? What
evidence led Rutherford to conclude that the nucleus is positively charged? What
evidence led him to conclude that the nucleus is very dense?
What did Niels Bohr’s model of the atom look like?
It would be difficult to build an actual scale model of an atom because of the following
problems:
If the nucleus were the size of a marble, the whole atom would be the size of a football
field and the marble would need to weigh millions of tons. Also, the electrons move so
fast that they form a cloud or electric field around the atom. Electrons do not orbit neatly
like planets in a solar system, but instead orbit in strangely shaped three-dimensional
regions around the nucleus in which there is a probability of finding the electron.
Read about the composition of the atomic nucleus on page 75.
Read about Atomic Number on page 77. What gives atoms their identity?
Where are the electrons, protons, and neutrons in an atom?
What is the relative electric charge of each of these particles?
What is the relative mass of each of these particles? (See table one on page 76)
Read about The Mole, Avogadro’s number, and Molar Mass on page 83. Practice
changing grams to moles, moles to grams, grams to atoms and atoms to grams. (Page 8487)
Remember that you can’t change atoms to grams or grams to atoms without first
changing to moles.
(You really only need to memorize two facts to do these problems. 1. There are 6.022
*10 23 atoms in one mole of any element. 2. The mass in grams of one mole of any
element can be found by looking it up on the periodic table.)
1.3 (Periodic Table)
(Read pages 16—20 in your text.)
The periodic table is organized by increasing atomic number (# of protons in the
nucleus). The atomic mass is the number of protons plus neutrons. In a neutral atom,
the number of protons equals the number of electrons. Flourine’s atomic number is 9 and
its atomic mass is 19. Therefore flourine has 9 protons, 9 electrons, and 10 neutrons ( 9
protons + 10 neutrons = 19 atomic mass units). Atoms with the same number of protons
but different numbers of neutrons are called isotopes. For example, carbon-12 has 6
protons and 6 neutrons, but carbon-13 has 6 protons and 7 neutrons. Carbon-12 and
carbon-13 are isotopes.
On the periodic table, vertical columns are called groups and horizontal rows are called
periods. Elements in the same group have similar chemical behavior because they have
the same number of electrons in their outermost energy level. The electrons in the
outermost energy level are called the valence electrons. Group 1 (the alkali metals) are
all very reactive, soft, metals. They each have only one valence electron. Group 2 (the
alkaline earth metals) are less reactive than the group one metals and are a little harder
and more dense. Group two elements each have two valence electrons.
Group 17 elements (the halogens) are very reactive non-metals. Group 17 elements each
have 7 valence electrons. Group 18 elements (the noble gases) are all unreactive gases.
They each have a completely filled outer energy level of eight electrons.
The stair-step line that begins between Al and Si divides the periodic table between
metals on the left and non-metals on the right. The elements that border the stair-step
line have properties of both metals and non-metals and are known as metalloids or
semimetals or semiconductors. Francium is the most reactive metal. Flourine is the most
reactive non-metal.
The size of atoms generally increases as you move down a group. This is because as you
move down the table, the electrons must occupy energy levels that are farther from the
nucleus.
2.1 (Quantum Theory)

Wavelength is the distance from the top of one wave to the top of the next wave.
Frequency is the number of waves that pass a certain point in one second. The
higher the frequency the greater the energy and the shorter the wavelength.
Radiation with a longer wavelength has less energy (less frequency). Within the
visible light spectrum (ROYGBIV), red light has the longest wavelength (lowest
frequency) and violet light has the shortest wavelength (greatest frequency).
Therefore, red light has less energy than violet light. Our eyes can’t see
wavelengths longer than red light (infrared) or shorter than violet (ultraviolet).
See pages 97-98

The electrons in an atom exist in certain energy levels, or shells, around the
nucleus. The energy level nearest the nucleus is the lowest energy level. The
energy level generally increases with increasing distance from the nucleus. An
electron will occupy the lowest energy level possible if that level isn’t already
filled with electrons. When atoms are excited (by electricity, heat, or light of the
right frequency), the electrons may absorb enough energy to jump up to a higher
energy level. When the electron falls back down to a lower energy level it emits
(gives off) energy in the form of a photon of light. The energy (frequency) of the
emitted photon depends on the distance the electron falls. Electrons emit photons
of greater energy (higher frequency, shorter wavelength) when they fall from the
highest energy levels to the lowest levels. A photon of violet light has more
energy than a photon of red light. See pages 102-103

The amount of energy that an electron needs to jump up to a higher level is called
a quantum of energy. The amount of energy emitted by an electron falling from
a higher to a lower level is also called a quantum of energy. When an electron
changes energy levels it is called a quantum leap. Electrons can only exist within
certain energy levels. They can’t be found between energy levels. Each element
has its own unique energy levels that its electrons can be in. Therefore, each
element gives off its own unique mixture of wavelengths of light when excited. If
those wavelengths are separated by a prism, a distinct pattern of colored lines can
be observed called an emission spectrum. Each colored band in the spectrum is
formed by one of the many possible energy transitions the electrons make as they
fall from higher to lower levels. See pages 100-101

Because each element gives off its own unique blend of wavelengths when
excited, scientists can identify unknown chemicals by heating chemicals in a
flame and comparing the colors to those emitted by known elements.
(2.2) Nuclear Chemistry
Nuclear reactions are the result of changes inside the nucleus of an atom. When the
nucleus of an atom is unstable, it tends to decay, or fall apart. When a nucleus decays, it
gives off radiation in the form of particles and energy. Generally, the atoms with the
largest nuclei are the most unstable. When an atom’s nucleus decays it often changes the
number of protons in the nucleus. Therefore, it also changes the identity of the atom.
The half life is the time it takes for half of a sample of radioactive material to decay.
Study the graph at the top of page 688. The red dots represent the original radioactive
element. The grey dots represent the element it is changing into as it decays. Why does
the graph have a curved shape?
When a nucleus decays it can give off many types of radiation:
Alpha particle—two protons and two neutrons (a helium nucleus). Mass of 4 amu.
Charge of + 2. Low energy—cannot penetrate a piece of paper.
Beta particle—an electron (This results from the decay of a neutron into a proton and an
electron. The proton generally stays in the nucleus and the electron is given off as a beta
particle.) Mass of zero. Charge of -1. Can penetrate paper and skin, but not lead or
glass.
Gamma radiation—high energy radiation, very short wavelength, very high frequency.
No mass, no charge. Can be blocked only by thick layers of lead, concrete, or both.
The force that holds protons to protons, protons to neutrons, and neutrons to neutrons
inside a nucleus is called the strong nuclear force. This force of attraction operates only
within a distance of a few proton diameters, but it is a very powerful force. (If it wasn’t
so strong, the positively charged protons would all repel each other because like charges
repel.) The strong nuclear force is what gives a nuclear reaction its energy. A nuclear
reaction releases thousands of times more energy than a chemical reaction. A chemical
reaction involves only the electrons around atoms. Chemical reactions do not affect the
nucleus. In a nuclear reaction, some of the matter inside the nucleus is changed into
energy. In the famous equation E=mc2, the E is energy and the m is mass. In the
chemical reactions that happen in the world around us everyday, matter doesn’t change to
energy and energy doesn’t change to matter, but in a nuclear reaction matter can change
to energy and energy can change to matter.
Fission and fusion are two different types of nuclear reactions. Which one is happening
in the sun? Which one happens in a nuclear power plant? (see pages 697—699)
(3.1) Valence Electrons and Bonding
Valence electrons are the electrons in the outermost shell. It is the valence electrons that
are involved in forming bonds with other atoms. Elements in group one have 1 valence
electron. Group two elements have 2 valence electrons. Group thirteen has 3, group
fourteen has 4 and so on. Atoms are most stable if they have eight valence electrons (an
octet). Group 18 elements all have an octet so they are very stable. An atom will react
(bond) with another atom if it makes it more stable. For example, Na (sodium) has one
valence electron in its 3rd energy level. If sodium loses its one outer electron by giving it
up to another atom, sodium will be more stable because it now has eight valence
electrons (in it’s 2nd energy level.) But now sodium has one less electron compared to the
number of protons in its nucleus so it has a positive charge and is now called a sodium
ion. Chlorine is in group seventeen, so it has 7 valence electrons. If chlorine gains one
more electron it will have a full octet of electrons and will be more stable. But now
chlorine has a negative charge because it has an extra electron compared to the number of
protons in its nucleus and is now called a chloride ion.
A positively charged sodium ion and a negatively charged chloride ion will form an ionic
bond. Ionic bonds are formed when atoms gain or lose electrons to form ions. Ionic
compounds form when a metal bonds with a nonmetal.
Covalent bonds are formed when atoms share the electrons in the bond. Covalent
compounds form when two nonmetals bond.
Metallic bonds are formed when metals bond with metals. In a metal, the electrons are
shared with all the atoms in the metal. The electrons in the outer levels of metal atoms
can freely move from one metal atom to another. This is why metals conduct
electricity—electrons can move through the metal.
3.2 (Compounds)
Two or more elements chemically bonded together form a compound. H2O is a
compound made of two atoms of hydrogen and one atom of oxygen.
Physical properties can be observed without a chemical reaction taking place. For
example, we can observe the color, hardness, melting point, boiling point, and
conductivity of copper without copper reacting with anything else. Chemical properties
describe how a substance reacts with other substances. Iron’s interaction with oxygen to
form rust is a chemical property of iron. Nitrogen’s lack of reactivity with other
substances is a chemical property of nitrogen.
The physical properties of a compound are often very different from the physical
properties of the elements that make up the compound. Sodium (Na) by itself is a soft,
silvery metal and chlorine by itself is a pale, yellow gas with a strong smell. But the
compound sodium chloride (NaCl) is a white, hard, odorless, compound that tastes great
on fries.
The chemical properties of a compound are also very different from the chemical
properties of the elements that make up the compound. Sodium (Na) reacts violently
with water and chlorine reacts dangerously with human tissue, but the compound sodium
chloride (NaCl) does not react violently with water and will not corrode human tissue.
Just changing the proportions of atoms in a compound can also change the properties of a
compound. For example, water (H2O) has properties that are very different from
hydrogen peroxide (H2O2) even though they are both made of hydrogen atoms and
oxygen atoms. Only the ratio of oxygen to hydrogen is different.
3.3 (Properties of Compounds, molecular geometry, and polarity)
Type of Bond
Formed by
Malleability—
ability to be
hammered into
a sheet
Conductivity—
ability to
conduct
electricity
Solubility –
ability to be
dissolved in
water
Ionic
Metal +
Nonmetal
No- Ionic
compounds
generally
shatter when hit
with a hammer.
Yes-- if
dissolved in
water.
Yes, but some
ionic
compounds are
not very
soluble.
Covalent
Nonmetal +
Nonmetal
Not usually
NO
Sometimes
Metallic
Metal + Metal
Yes
Yes
No
A polar molecule is a molecule where the electrons in the bonds between the atoms are
pulled more strongly toward one side of a molecule than the other.
Water (H2O) is a polar molecule because the oxygen has a stronger attraction for the
electrons in the bond than do the two hydrogens. As a result, the electrons spend more
time near the oxygen side of the molecule and the oxygen side of water is slightly more
negatively charged than the hydrogen side. The molecular geometry of a water molecule
is bent.
Ammonia ( NH3) is also a polar molecule because nitrogen has a stronger attraction for
the electrons than do the three hydrogens. The nitrogen side of the molecule is slightly
more negatively charged than the hydrogen side. The molecular geometry of an
ammonia molecule is pyramidal.
Methane (CH4) is non-polar because it is a symmetrical molecule. The carbon is in the
center so even if it pulls the electrons toward itself, the molecule as a whole will not have
a negative side and a positive side. The molecular geometry of methane is tetrahedral.
Polar molecules such as water tend to stick together because the positive side of one
molecule is weakly attracted to the negative side of another molecule. These weak
intermolecular (between molecule) attractions are called hydrogen bonds and give
water unique properties such as:
surface tension (this is why belly-flops hurt)
capillary action (water can creep up thin tubes)
high boiling point --The “stickiness” of polar molecules make it more difficult to
separate them from each other to form a gas. This is why you have to get water very hot
before it boils. The more polar the molecules, the higher the boiling point.
4.1 and 4.2 (Chemical Reactions)
Evidence that a chemical reaction has taken place might include a change in
temperature, production of bubbles, production of light, the formation of a precipitate,
etc. Rusting of metals, cooking food, bleaching, and cleaning are examples of everyday
chemical reactions. (Boiling water is not a chemical reaction. It is a physical reaction
because the water molecules do not split into hydrogen and oxygen. It is still water—its
just water in the form of a gas. Only the weak intermolecular hydrogen bonds have been
broken. The much stronger covalent bonds have not been broken.)
Reactants are the chemicals before the reaction takes place and products are produced
after the reaction has taken place. Usually the reactants are written to the left of the arrow
and the products to the right.
A chemical equation describes the molar proportions of reactants and products in a
chemical reaction. Consider this equation.
2H2 + O2 
2H2O
This means that two moles of hydrogen gas combine with one mole of oxygen gas to
make two moles of water. The molar ratio of hydrogen gas to oxygen gas is 2:1. The
molar ratio of oxygen gas to water is 1:2.
The properties of the reactants are often very different from the properties of the
products. Hydrogen is a flammable gas, and oxygen is a gas that causes things to burn.
But bond them together and you get a product that is a liquid at room temperature that
puts out fires. The point is that the properties of the reactants are often very different
from the properties of the products even though they are made of the same atoms.
Conservation of Mass—Atoms are not created or destroyed in chemical reactions. They
just change partners. If we could mass the reactants in a sealed, airtight container and
make them react without opening the container, we should find that the total mass before
the reaction is the same as the total mass after the reaction.
Conservation of Energy- Energy is not created or destroyed in a chemical reaction. It
just changes into different forms of energy. For example, there is chemical energy stored
in the bonds between hydrogen atoms in hydrogen gas and between the oxygen atoms in
oxygen gas. When they combine to make water some of the energy is transformed into
heat, light, sound, and motion energy and some of the energy is now found in the new
bonds of the water molecules. The heat, light, sound, and motion energy is still
somewhere in the universe, so the total amount of energy before the reaction is the same
as the total amount after the reaction. If a reaction gives off heat energy to the
environment it is called an exothermic reaction. If the reaction takes in energy from the
environment it is called an endothermic reaction. An endothermic reaction will feel cold
because heat energy is leaving your hands and going into the reaction. Changes in
temperature, light, sound, and motion are all evidence of energy transformations in
chemical reactions.
Chemical energy can also be changed to electrical energy. When an ionic compound
forms, one element donates its electrons to another element. If we separate the element
that is donating from the element that is accepting and connect them with a wire, then the
electrons have to go through the wire to get from one to the other. Electrons moving
through a wire make electricity! This is how a battery works. Two different metals
(electrodes) are placed in an electrolyte solution (a solution containing ions) and
connected by a wire. The two electrodes are separated by a porous barrier. Electrons
will flow from one metal to the other through the wire. When the electrons get to the
other electrode they are taken up by positive ions in the solution. Ions in the solution can
move across the barrier to equalize the difference in charge so that the electrons can keep
flowing through the wire.
An Electrochemical Cell
Half-reaction
Half-reaction
5.1 and 5.2 (Reaction Rates and Dynamic Equilibrium)
The rate (speed) of a chemical reaction depends on the frequency of collisions, the energy
of the colliding atoms or molecules, and the orientation (position) of atoms or molecules
relative to each other. Higher temperatures increase reaction rates because it increases the
frequency of collisions between the reactants. Smaller particle size increases the surface
area so there are more surfaces where collisions can take place. The more concentrated
the reactants, the more frequently the molecules will collide. (See figure 6 on page 569)
A catalyst is anything that speeds up a reaction, but is not one of the reactants or
products. The catalytic converter in the exhaust system of a car has metals such as
platinum and rhodium that act as catalysts. They speed up reactions between oxygen in
the air and pollutants coming out of the exhaust. ( Page 579) Enzymes are catalysts in
living cells. Catalysts increase reaction rates by lowering the activation energy of a
reaction.
Activation energy is the energy needed to start a reaction going. A balloon full of
hydrogen and oxygen gases will react explosively, but it needs a little heat energy from a
burning match to get it started. The burning match provides the activation energy. Once
the reaction starts, enough energy is produced by the reaction itself to keep the reaction
going.
Study the diagrams and graphs in your book on the following pages:
Diagram 563
Graph on 564 (The bump on the graph show the activation energy needed to get the
reaction started.)
On a line graph, the steeper the slope of the line, the faster the rate of the reaction.
Be able to explain which graphs show exothermic reactions and which show endothermic
reactions for the graphs on page 581. In an exothermic reaction the reactants have more
energy than the products because energy is released into the surrounding environment
during the reaction. In an endothermic reaction the products have more energy than the
reactants because energy from the surrounding environment goes into the reaction.
2H2 + O2  2H2O + energy
(This reaction gives off energy. It is exothermic.
All it needs is a little activation energy and it goes all by itself.)
If enough energy is added to water, the reverse can also happen:
2H2O + energy  O2 + 2H2 ( This reaction will only go if a lot of energy is
continuously added. It is endothermic.)
Read the first paragraph on page 589.
Many chemical reactions are reversible under ordinary conditions. For example,
hydrogen gas and iodine gas react to form hydrogen iodide gas.
H2 + I2   2HI
In this reaction, not all of the reactants are converted to HI.
Some of the HI is converted back to H2 and I2. When the rate of the forward reaction
equals the rate of the reverse reaction the reaction is said to have dynamic equilibrium.
The reactions don’t stop! The forward and reverse reactions keep going, but at the same
rate!
Now read the first paragraph at the top of page 598.
A change in concentration can cause a shift in equilibrium.
Consider the following equation.
A + B   C + D
If more A is added to the reaction, it will cause the reaction to go to the right. (More C
and D will be produced.)
If more B is added to the reaction it will also cause the equilibrium to shift to the right.
If more C or more D is added, the reaction will be pushed to the left. ( More A and B will
be produced.)
Temperature can also cause a shift in equilibrium.
Consider the following reaction at dynamic equilibrium.
N2 + 3H2   2NH3 + 92 kJ
( kJ is kilojoules, a joule is a unit of energy)
If heat is added to this exothermic reaction it will drive the reaction to the left.
Consider this reaction at dynamic equilibrium.
556 kJ + CaCO3   CaO + CO2
Adding heat to this endothermic reaction will drive it to the right.
6.1 (Solutions)
The solvent is what does the dissolving and the solute is what is dissolved in the solvent.
For example, if sugar is dissolved in water, then sugar is the solute and water is the
solvent. In a solution, the solute particles are evenly spread out through the solvent so
that the mixture has the same composition throughout. See page 401—402.
Solutions don’t always have to be liquids. Gases can be dissolved in liquids, gases can
be dissolved in other gases, and solids can be dissolved in other solids. Examples -- page
402.
The concentration of a solution is a measure of the amount of solute in a given amount
of solvent. A dilute solution has a relatively small amount of solute and a concentrated
solution has a relatively large amount of solute. Concentration can be expresses in
molarity or molality.
Molarity is the number of moles of solute in one liter of solution. Read about molarity
on page 418. Molality is the concentration of a solution expressed in moles of solute per
kilogram of solvent. See page 422.
The rate at which a solute dissolves in a solvent depends on temperature, agitation
(stirring or shaking), and particle size (powdered sugar dissolves faster than a sugar
cube.)
The concentration of pollutants in the environment is often expressed in ppm (parts per
million).
6.2 (Colligative Properties)
Properties that depend on the concentration of solute particles but not on their identity are
called colligative properties. The temperature at which a solution boils or freezes is a
colligative property. For example, dissolving sugar in water raises the boiling point and
lowers the freezing point. See graph on page 446.
Study “Electrolytes and Colligative Properties” on page 453. Pay careful attention to
Figure 9 at the bottom of the page. Which salt would lower the freezing point the most-NaCl or CaCl2? Which one would raise the boiling point the most? If you want to melt
ice should you lower the freezing point or raise the freezing point? Why do we put salt
on icy roads? Which salt would be best for this purpose?
6.3 (Acids and Bases)
An acid increases the concentration of hydrogen ions (H+) when it dissolves in water and
a base increases the hydroxide ion (OH-) concentration when it dissolves in water. If
there is more H+ than OH- then the solution is acidic. If there is more OH- than H+ then
the solution is basic. When H+ = OH- then the solution is neutral. On the pH scale, a pH
of 0 is very acidic, a pH of 14 is very basic, and a pH of 7 is neutral. See the pH scale on
page 512. A pH indicator is a compound that will change colors as the pH of a solution
changes. Learn how to perform a titration by reading pages 515—521.