CHEMISTRY

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CHEMISTRY

• Chemistry is a huge topic. You will be asked to
  do lots of worksheets, problem solving. You will
  take quizzes and tests. You will be asked to
  memorize important material, There will be video
  presentations and MAYBE a trip to the chem labif
  it can be arranged.
• Chemistry is the study of the composition of the
  universe.
• It studies what the world is made of!
• Chemistry began not so much as a science as it
  was a pseudoscience.
• A pseudoscience is a false science.
• If we argue that true science requires a search
  for the truth via the use of the scientific
  method, the quantification of knowledge that it
  is published and available to all then a
  pseudoscience does NOT do those things and thus
  is a FALSE (pseudo) science.
• False studies like UFO claims, phrenology and
  astrology are examples of pseudosciences. They do
  not follow the scientific method, their work
  cannot be isolated to one variable, it cannot be
  duplicated, it is not scrutinized by members of
  the international scientific community, etc. etc.
• There are rules and scientists must play by the
  rulesso must studies that claim to be sciences.

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Alchemy

• It turns out that a core true science like
  chemistry started out really as a pseudoscience
  called alchemy.
• Alchemy is all about the search for two things
• 1. The elixir of life
• 2. The process that would turn anything into
  gold.
• It was all very secret, coded, symbolic. This is
  truly the antithesis of a true science.
• Those of you into Harry Potter and the LORD OF
  THE RINGS, into wizards and spells and the like
  are all drawn from the stereotypes of ALCHEMISTS.
  Wizards who knew magic were alchemists who knew
  something of chemistry but werent willing to
  share the know-how with anyone else.
• They never found the elixir of life.
• They never could spin straw into gold as
  Rumplestiltskin tried to do.

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The journey from alchemy to chemistry

• Along the way as wizards and magicians and the
  like tried to find the elixir of life and a way
  to turn anything else into gold, they learned a
  lot of other things, they invented a lot of
  equipment and they began to find the real world
  as interesting a search as the search for the
  elusive.
• We still use a lot of the glassware they
  invented, we still use a lot of the processes
  they pioneered.
• Alchemists became chemists when they began to
  write things down in the vernacular, when they
  studied the world around them and when they began
  to publish their results so their peers could
  scrutinize and duplicate.

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Soin chemistry

• The study of chemistry begins with the base of
  operations, the bible for all chemiststhe
  Periodic Table of Elements.
• Without exaggeration I can say that on a single
  piece of paper there is a list of EVERYTHING IN
  THE UNIVERSE. THERE IS NOTHING ELSE.
• Notice various Periodic Tables. What differences
  among them do you notice?
• They are merely cosmetic, merely a function of
  the date of publication.
• I will offer 50 EC points if you can name one
  thing that is NOT on an updated periodic table.

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Editing a periodic table for use in this class

• Miss Malley will give you a copy of a Periodic
  Table that we will use in this classroom.
• We will mark the stepline.
• We will distinguish between columns and rows.
• We will number the rows from 1-7 and explain
  their significance.
• We will number the columns from 1A-8A and explain
  their significance.

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Dmitri Mendeleev

• The Father of the Periodic Table was the
  Russian Dmitri Mendeleev.
• Among others, he tried to organize stuff.
• Mankind has always liked to organize in order to
  control, to understand. So, look around this
  room. Look at all the different things. How would
  you begin to classify, organize, inventory
  everything in this room. What plan would you use?
  How would you visually design the inventory so
  that you could easily find some item, any item?
  That was the challenge of chemists. They studied
  things all thingshow would one BEGIN to
  organize EVERYTHING?

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Atomists

• Eventually it came to be that scientists agreed
  that everything was made of atoms.
• Whats an atom?
• Well, a few thousand years ago men speculated
  about the smallest particle that made up all
  things. A Greek by the name of DEMOCRITUS was
  among them. What he speculated was that if you
  took a chunk of something, anything, and you cut
  it in half and in half and in half and in half
  etc. eventually you would come to the smallest
  particle that could not be cut, the tiny
  fundamental marble-like particle he called
  atomos.
• Atomos is Greek for indivisible, not
  divisible.(not invisibleinDIVISible.)

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Atoms

• If everything is made of atoms then what makes
  gold different from oxygen and zinc different
  from lead. Were there different ATOMOS?
• By the 20th C we realized the atom was NOT
  indivisible. The atom itself had parts
• Every atom was made up of smaller particles,
  protons, neutrons, electrons.
• We thought they were indivisiblecould not be
  cutthen we found quarks. Quarks are even smaller
  particles that make up P.N.e.
• So, what is the smallest, indivisible particle??
• Havent found it yet.

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And what IS the difference between gold and
oxygen??

• On the P.T. there are 2 numbers that identify
  every element. The smaller of the 2 numbers is
  called the ATOMIC NUMBER. This number identifies
  the element. This number is the number of protons
  in the element.
• So Li has..
• Gold has
• Oxygen has.
• Sodium has..
• The difference between Lithium and Gold is the
  number of protons in each atom of the element.

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What about the bigger number?

• The larger of the 2 numbers is called the ATOMIC
  MASS NUMBER in most books, but in some texts it
  may be called the ATOMIC WEIGHT.
• The larger number is the TOTAL number of Protons
  and NEUTRONS.
• Neutrons and protons are jammed together in an
  area called the nucleus.
• Neutrons have NO electric charge. Protons have a
  POSITIVE electric charge.
• All protons have the same positive charge so they
  do NOT want to stay close togetherlike charges
  repelthey would fly apart if they could BUT
• Like cowboys herding cattle, neutrons keep the
  protons in the nucleus. So there is this dynamic
  tension in every atom. Electrons spinning,
  protons and electrons pulling on one another
  while the protons in the nucleus are repelling
  one another.

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And where are the electrons?

• We said there were 3 common particles that make
  up every atom, Protons, Neutrons and electrons.
• Electrons are very tiny.
• They orbit the nucleus of every atom.
• Protons and Neutrons are in the nucleus, in the
  CENTER, electrons spin in orbits around the
  center nucleus.
• The number of electrons is the same as the number
  of protons in every atom.
• The NUMBER OF PROTONS equals the NUMBER OF
  ELECTRONS.

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Electron orbits

• Electrons spin around the nucleus not unlike
  planets around the sun. Electrons travel at
  different distances from the nucleus just like
  some planets are closer or farther from the sun.
• There are rules for placing electrons in orbit
  around the nucleus.
• 1. Only 2 electrons can fit in the first energy
  level, the first orbit.
• 2. UP to 8 electrons can fit in the second energy
  level.
• 3. Up to 8 electrons is stable for electrons in
  the third energy level.
• 4. But keep in mind that the number of electrons
  you must distribute is equal to the number of
  protons that identify the element.

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Atomic models

• We cant see an atom, not even today with all of
  our equipment. The best we can get is just a
  blur. So over the years scientists have developed
  models which try to give us a picture of what an
  atom looks like.
• How do we know if they are good models?
• Accurate?
• The models are good if we can make predictions
  based on the model and real matter behaves just
  the way we predict they will behave according to
  our model.
• Over the years there have been many models.
• We could start with Democritus who said the
  atomos was the indivisible particle.

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Daltons model

• John Dalton was a teacher.
• Over time he studied the behavior of matter and
  suggested his verbal model of the atom.
• Dalton also thought the atom was
  atomosindivisiblea hard marble
• BUT
• He went on to suggest several new ideas
• 1. Atoms of the same element are all alike.
• 2.Atoms of different elements are different.
• 3. Atoms of different elements can join together
  in small whole number ratios to form compounds.

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Thomsons model

• JJ Thomsons model of the atom included the newly
  discovered particle called the electron.
• The electron was discovered in the cathode ray
  tube near the turn of the century. Its discovery
  proved the atom was NOT indivisible but had
  parts. There were SUBATOMIC particles.
• Thomson reasoned also that since most matter was
  neutral, if this negatively charged particle
  existed then a positively charged particle must
  also exist to make matter neutral.
• He envisioned the atom to be like chocolate chip
  cookie dough. The dough was the positive part of
  the atom and the chocolate chips were the
  electrons.

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Dr. Rutherford said

• Rutherfords model of the atom came about as a
  result of an elegant experiment in 1911 called
  the gold foil experiment.
• He had engineers pound a bit of gold until it was
  VERY thin. He fired POSITIVELY charged particles
  into this gold foil.
• 99.999 of those particles went through the
  foil unhampered. Straight through.
• Once in awhile a particle would come bouncing
  straight back at him.
• Once in awhile a particle would be deflected
  off at some angle.
• What the world realized was that the atom was
  made of a charged, very dense, very SMALL
  nucleusa center. The electrons must be outside
  that nucleus somehow. And in between the nucleus
  and the negative electrons there was NOTHING!!!
• It was Rutherfords gold foil experiment that
  began to suggest that the world was really an
  illusion, that the world was mostly made of EMPTY
  SPACE.
• Everything is made of atoms and the atom is
  99.999 empty space thus everything is
  mostly..
• His experiment also proved that most of the mass
  was in the nucleus. Electrons contributed
  insignificant mass to the atom.

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Niels Bohr

• In 1913 Niels Bohr (Danish) suggested another
  model. This is the one most useful to us.
• In the Bohr atom, the nucleus contains protons
  and neutrons.
• The electrons orbit the nucleus in orbits at
  different distances like planets orbiting the
  sunthey dont all orbit in the same path but are
  spread out some closer to the sun, some farther.
• Electrons are like that.
• It turns out that because matter is neutral, the
  number of positive charges (P) must be equal to
  the number of negative charges (e-).
• Over the years we have realized that 2 e- can
  spin in the closest orbitcalled an energy level.
• Up to 8e- can orbit in the second energy level.
• Up to 8 e- can orbit in the third energy level
  and we wont go much beyond that as we sketch
  atoms.
• One more point, the farther out the electron is
  from the nucleus, the more energy it has. The
  closer it is to the nucleus, the less energy the
  electron has.

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Sketching atoms

• We will use the BOHR atom as our model.
• Niels Bohr developed this particular model.
• Miss Malley will now turn off the system and we
  will learn how to sketch atoms from 1 - 20.

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Properties

• Go to the bulletin board and get the picture.
  Ill give you 10 EC points for the correct one.
• Butthat would be kind of difficult because???
• YOU NEED TO NARROW DOWN THE CHOICES
• YOU NEED MUCH MORE INFORMATIONYOU NEED
  PROPERTIES
• PROPERTIES ARE WORDS THAT IDENTIFY, DESCRIBE, AND
  DISTINGUISH.

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Properties identify, describe, select

• Words that describe and identify and select
  particular objects from among others are called
  properties.
• They include physical properties
• Color, odor, luster, state, density, texture,
• Conductivity, malleable, ductile, magnetic.
• And there is ONE chemical property
• The number of electrons in the OEL determines how
  the atom will behave when forming
  compoundschemical reactivity.

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Properties include

• Solids , liquids, gases have identifying
  properties.
• Solids have a definite shape and volume.
• Liquids have a definite volume but take the
  shapes of their container.
• Gases spread out to occupy the entire space
  available so gases have neither a definite shape
  nor volume.

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Things can change

• It turns out there are two ways that matter can
  be changed. There are physical changes. There are
  chemical changes.
• Physical changes are any changes you might make
  in an object that do NOT change the identity of
  the object. So you must ask yourself after the
  change is made Did I end up with the same
  substance I started with? If the answer is YES
  then that describes a physical change.
• If you end up with an entirely different
  substance that has different physical and
  chemical properties than the substanve you
  started with then that describes a CHEMICAL
  change.

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Physical changes

• You tear a piece of paper. After you do that you
  still have a paper. You have not altered the
  identity of the substance.
• If you cut, saw, shred, tear,etc then those are
  physical changes because when you are done you
  still have the original substance.
• After you melt butter, you started with butter,
  you end up with butter. So freezing, boiling
  melting are all physical changes.
• A change in density is a physical change.

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Chemical changes

• In all chemical changes you will end up with
  something VERY different from what you started
  with.
• Take some hydrogen, odorless, colorless EXPLOSIVE
  gas and add it to some oxygen, odorless,
  colorless gas that supports combustion (burning).
  After you do that you end up with a clear liquid
  you use to put out fires called water. Water is
  VERY different from EITHER hydrogen or oxygen.
• Other things that produce very different products
  include baking, cooking, exploding, burning,
  tarnishing, rusting, corroding,all chemical
  reactionsthe forming of compounds, the
  destruction of compounds, the rearrangements of
  compounds, the production of light,

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Now, back to the P.T.

• The stepline divides the P.T. into..and.
• Elements that sit ON the stepline are called
• The column number tells us..
• The row number tells us..
• The atomic number tells us..
• The atomic mass number tells us.
• The man who designed the first modern periodic
  table was
• The difference between gold and oxygen is.
• The difference between an atom of sodium and an
  atom of lithium is..
• The smallest part of an element is.
• The word atom comes from.
• The atom is made ofcommon particles
• Consider the differences between metals and
  nonmetals. Characteristics include?
  M

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Properties of M and NM

• A metal is generally
• Solid at room temperature
• Solid with a luster
• Malleable
• Ductile
• Silvery in color
• On the left side of the stepline on the P.T.
• Have fewer electrons in the outer energy level of
  the atom.
• Likely to give away electrons as compounds are
  formed
• SOME METALS ARE MAGNETIC
• Nonmetals are none of those things.

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More, More of the P.T.

• Col. IA, Group I are called the ALKALI metals.
  They all have only 1 e- in their OEL and thus are
  looking to get rid of it! They happily form
  compounds with any element in Col . VIIA Metals
  form a 1 ion while the Col. VII halogens form
  a -1 ion.
• Col.I Col. VII produce SALTS.
• Every element in Col IA is soft, silvery, low
  density, melt at low temps and highly REACTIVE

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And Col IIA

• These are called the ALKALINE EARTH METALS
• They all have 2 e- in their OEL so that they try
  to get rid of 2 OEL e-. Thus they are very
  reactive, eager to form compouhnds, but not
  kquite as eager as those in Col IA since these
  elements are closer to achieving 8 e- in the
  OEL.
• Col. IIA metals will form compounds very easily
  with those elements in Col VIA.

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Transition elements/metals

• Groups 3-12 is that big middle group of metals.
• These do not follows the rules quite as nicely as
  the Col. A elements.
• These metals are mostly shiny, have high melting
  points, are good conductors of heat and
  electricity. They make ionic compounds with
  nonmetals.
• These metals are often found in ores dug out of
  the ground.

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RARE EARTH ELEMENTS

• These are metals that were pulled out of the main
  P.T. and put at the bottom in two row. This was
  done both because the elements are rareyou
  probably wont run into any of these in your
  lifeANDbecause it made the table able to fit on
  a single piece of paper.
• The two rows were called the Lanthanide and
  Actinide series.
• Generally Lanthanides are from 51-71 though this
  may vary slightly on PT
• Generally the Actinides are 90-103.
• Keep in mind that the last naturally found
  element is 92 Uranium beyond that the elements
  are man made by bombarding large nuclei with one
  more Protonrecall that it is the number of
  protons that identify the element.

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Col IIIA

• This is claled the Boron Group only because Boron
  is the first element in the col. On some PT it is
  col 13.
• Boron is a metalloid. It is brittle,black.
• Every element below Boron is a metal though, just
  to the left of the stepline.
• The most common metal that comes from the earth
  is Aluminum in this group.

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Col. IVA

• Called the Carbon group. Carbon is clearly a NM
  But Si is a metalloid, it sits ON the stepline.
• Silicon compounds make up 60 of the Earths
  crust.
• Tin and lead are both metals.

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Col. VA

• Called the Nitrogen group.
• Nonmetal, N is a diatomic element that is 80 of
  our air..it also fills the tires of airplanes. It
  does not combine easily with other elements.
  Nitrogen is part of our bodies in proteins.
• Other elements include P, a NM
• Arsenic is a poison.
• Sb, Bi, are both metals.

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Col. VIA

• The oxygen group is very important to usto
  breathe. It only make sup 20 of the air but
  essential. Most oxygen is combined with Silicon
  in rocks.

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Col. VIIA

• Halogens.
• Col. 7A elements are salt formers. They love to
  make salts with metals in 1A.
• These are all very reactive nonmetals. Fluorine
  is the MOST reactive of all the nonmetals.

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Col. VIIIA

• The Noble gases are all in col 8A.
• Group 18
• These gases are used in signs.
• These gases have 8 e- in the OEL and thus are
  stable and thus make NO compounds with other
  elements.

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Hydrogen

• Notice that Hydrogen is set off by itself. It is
  often set above Col 1A.
• H is a NONMETAL
• It is a diatomic gas nonmetal
• BUT
• We put it in Colo. IA usually because it has 1 e-
  in its OELits ONLY ELand thus behaves a little
  like the elements in Col IA.
• It loses its 1 e- a lot!
• Hydrogen is the most abundant element in the
  UNIVERSE.

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ISOTOPES

• It turns out that
• Atoms of the same element have the same number
  of protons in the nucleus.
• Recall that the number of protons identifies the
  element.
• Element number 3 is .because..
• BUT.
• It also turns out that
• Although every atom of a particular element has
  the same number of protons, atoms of the same
  element can have different numbers of neutrons.
• For example although every atom of oxygen
  has.protons, one atom of oxygen might have 7
  neutrons, another atom of oxygen might have 8
  neutrons, another atom might have 6 neutrons. So
  there are 3 isotopes of oxygen in this example3
  isotopes, 3 versions of oxygen as it were..
• Carbon has .protons and.electrons. BUT some C
  atoms have 6 neutrons but other C atoms have 8
  neutrons. So we would say that carbon has two
  isotopes2 versions of carbon.
• You couldnt tell the difference among isotopes.
  They chemically behave identically.

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So what

• So what is the periodic table?
• What is an element?
• An element is a collection of atoms that all look
  alikeall have the same number of protons.
• An element is the fundamental building block of
  everything else.
• ALL things are either elements or compounds.

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And a compound is.

• A compound is a collection of 2 or more elements
  that have joined together to make something BRAND
  NEW.
• EVERYTHING then is either an element, on the
  periodic table or it is a collection of elements.
• Gold is an element. Water is a compound. Whats
  the difference?

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Elemental symbols and chemical formulas

• On the P.T. every element has a symbol of 1 or 2
  letters. Sometimes the symbol makes sense.O is
  oxygen. But Na is sodium because the symbol Na is
  from the Latin word Natrium.
• N is nitrogen but Hg is from the Latin
  Hydrargyrum which is Latin for Mercury.
• It is wise to learn the symbols of the most
  common elements since it will save you time in
  the long run.
• Compounds can also be written with shorthand
  symbols. NaCl is sodium chloride. H2O is water.
• We will talk much more about compounds as we move
  on.

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Why do elements form compounds at all?

• It turns out that compounds form at all because
  Nature Seeks Stability.
• So what does nature think is stable?
• Nature plays by something called the octet rule.
  That means that an atom is considered chemically
  stable if it faces the world with 8 e- in its
  outermost energy level.
• Atoms want 8 e- in their outer energy level.
• They will do whatever it takes to get a full
  outer energy level to face the world.
• It turns out that atoms can gain or lose
  electrons in order to face the world with a full
  OEL.
• Miss Malley will spend a good deal of time
  lecturing further on the how and why of compounds.

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Three types of compounds.

• An atom will do whatever it must in order to get
  a full outer energy level facing the world.
• Metals in Col. I, II, III have 1,2,3 e- in the
  OEL so it is easier for the atom to LOSE 1 or 2
  or 3 e- than it is for them to pick up 7e-, 6e-
  or 5e-.
• Nonmetals have 5,6,7 or 8 e- in their energy
  levels for Col. V, VI, VII, VIII. It is easier
  for those elements to pick up 3 or 2 or just 1 e-
  than to try and give away 5 or 6 or 7 e-. So NM
  want to GAIN e-.
• Col IV elements have no advantage in either
  gaining or losing e- so we will discuss their
  UNIQUE situation later.
• Col. VIII elements already HAVE 8e- in their OEL
  so they need nothing! Therefore they do NOT make
  compounds.
• Compounds are made because atoms seek stability,
  they seek a full OEL facing the world.
• Col. VIII A elements already have 8, they are
  stable, they are full, they do NOT form
  compoundsthats why some books call them the
  INERT gases. Col 8A elements are all gases and
  the word INERT describes and object that does
  NOTHING!
• If someone says you are inertthat is not a
  compliment.
• Some books call Col. 8A elements the NOBLE gases.
  Nobility means royaltyand the royals do not
  associate with the masses.do not mingle with
  others.so they do not form compounds.

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IONIC compounds

• Atoms gain stability by joining with other
  elements, other atoms so they have a full OEL.
• Atoms will gain or lose the number of electrons
  that will give them the full OEL.
• So when a metal atom seeks to lose some e-, a
  nonmetal that wants to pick up that number of e-
  will join with it to produce a COMPOUND
• This is an IONIC compound. An ionic compound is a
  METALNONMETAL.

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Covalent Compounds

• Covalents compounds are sometimes called
  MOLECULAR compoundsthey mean the same thing.
• A covalent compound is made up of 2 NONMETALS.
  When a Nonmetal and a Nonmetal join one is not
  strong enough to pull off e- from another NM. And
  NM dont really want to give away any e-. So what
  happens when a NM and a NM join is the e- are
  shared between them so that each of the atoms has
  influence over 8e-.
• This produces a compound called a covalent
  compound.

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What follows this will be the naming of
compounds, the definition of ions, polyatomic
ions and the PAI compounds, the binary and
ternary rules, writing formulas and predicting
compound formation.
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Whats an ION

• Atoms will gain or lose electrons in order to
  achieve a full OEL facing the world.
• The definition of an atom includes the notion
  that the number of Protons the number of
  electrons in every atom.
• BUT
• When at atom wither gains or loses electrons then
  the number of Protons NO LONGER equals the number
  of electrons.
• And THAT is an ion. An ion is an atom thqt has
  lost or gained electrons. An ion has an electric
  charge. It either has more electrons that protons
  so it has a NEGATIVE chare OR it has fewer
  electrons that protons so that it now has a
  POSITIVE electric charge.
• Atoms are NEUTRAL.

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Binary ionic compound

• A binary ionic compound
• This is a compound made of 2 elementsbinarytwo.
• Ionic means this is a metal attached to a
  nonmental.
• Compound is two or more elements making something
  very new and different so that atoms will become
  more stable.
• The metal wants to give away electronas and the
  nonmetal gains those electrons.
• In writing ionic compound formulas OXIDATION
  NUMBERS must equal zero.THIS WILL REQUIRE A LOT
  OF PRACTICE
• Oxidation numbers tell us how the atom will
  behave when forming compoundsit tells us how
  many electrons it wants to gain or lose.
• Name the metal, name the root of the nonmetal and
  end the compound in IDE
• Sodium chloridesodium is metal and chlor is root
  of NM and we end the binary name in IDEsodium
  chloride.
• Calcium chloride.
• Magnesium oxide

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Binary Molecular compounds

• Nonmetal attached to another nonmetal is a BMC.
  This is where Nonmetals SHARE OEL e-. In ionic
  compounds one atom loses electrons and the NM
  gains electrons. BUT in BMC no aytom gains or
  loses electrons. The two nonmentals simply SHARE
  electrons so that eacha tom has influence over
  enough electrons to make them more stable.
• We name the first nonmetal, name the root of the
  second nonmetal and end the name in IDE. ALL
  binary compounds end in IDE.

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MIXTURES

• There are elements which are pure substances,
  fundamental, basic, and made of all the same kind
  of atom. Hydrogen, oxygen , sodium , chlorine
• There are compounds which are pure substances
  made of 2 or more types of atoms joining together
  to make something new in order to achieve a full
  OEL facing the world. Water , salt
• Mixtures on the other hand are NOT pure
  substances. Mixtures do not require a recipe. A
  mixture is just a collection of stuff thrown
  together with no particular quantities required.
  No electrons are involved. All parts of a mixture
  keep their own identities. Nothing new is made.
  Salt water. Tossed salads stew vegetable soup

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Homogeneous vs Heterogeneous

• Substances, elements, compounds, mixtures can be
  described as either homogeneous or heterogeneous.
• Homogeneous describes any substance that has the
  same composition throughoutno matter where you
  take the sample it will be the same as every
  other sample. So elements are homogeneous. All
  atoms of an element are the same. Water is a
  compound. Compounds are homogeneousevery
  spoonful of water is the same no matter where the
  sample is from. All NaCl molecules are the same.
• Mixtures might also be homogeneous. Cream mixed
  into coffee produces an evenly mixed mixture. No
  matter where the sample is taken in that ocoffee
  cup the sample with be the same. Salt water is
  homogeneous, the salt is evenly distributed
  throughout the water. .All solutions are
  homogeneous mixtures. Solutions involve a SOLUTE
  mixed into a SOLVENT. The solvent DISSOLVES the
  solute until it is evenly mixed. The word
  DISSOLVE means to break into tiny pieces..
  Breaking is a physical changeso a solution is
  just a mixturea physical event.Not a chemical
  reaction
• So all elements, all compounds and SOME mixtures
  can be described as homogeneous
• Heterogeneous describes only mixtures. It
  describes mixtures that are NOT evenly mixed so
  that every spoonful is different. This would be
  a tossed salad, vegetable soup, chocolate chip
  cookies., stew. Each sample would be different.

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ALLOYS

• An alloy is a solution, a mixturea very specific
  mixture of metals melted together.
• We will make a list from the chemistry texts but
  alloys include steel, pewter, solder, brass, 24
  karat gold
• But it is just a mixture. Not a compound. No
  recipe is requiredjust a homogeneous solution

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CHEMICAL REACTIONS

• 1. Chemical reactions produce chemical changes.
• Chemical reactions can be written in shorthand
  using an equation form.
• We begin with REACTANTS and we end up with
  PRODUCTS.
• Products are VERY different from the reactants we
  started with.
• BUT everything must be accounted for. All the
  elements on the left must equal the elements on
  the right.
• Evidence that a chemical reaction has taken place
  include forming a precipitate, color change,
  formation of a gas, change in temperature.
• If heat, light or energy is given off then we
  call that an EXOTHERMIC REACTION. Things get hot.
• If heat is absorbed into the chemical reaction
  then we call that an ENDOTHERMIC REACTION.
  Things get Colder.

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Keep in Mind

• In chemical reactions, the energy is not in the
  atoms themselves but it is in the BONDS that are
  formed or broken. As when you digest food. It
  isnt the Atom itself you are really interested
  in, it is the energy stored in the atomic bonds
  that hold different atoms together. When bonds
  are formed, broken or rearranged it is the energy
  required to do that that is stored in or released
  from that action. And THAT is what we are after.

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Reactants yield Products

• In chemical equations reactants must equal
  products. Energy is always involved.
• All chemical equations must be balancedthe law
  of conservation of mass and energy is the rule.
  You cannot end up with more or less than what you
  started with and you cannot end up with different
  elements than what you started with.
• We balance chemical equations by using
  COEFFICIENTS. Coefficients are whole numbers we
  can place in front of compounds or fee standing
  elements. They cannot separate a compound, they
  must be IN FRONT OF wither the element or the
  compound.
• We learned that when writing a proper chemical
  formula, subscripts were essential to the recipe.
  The recipe for water or sugar or carbon monoxide
  or sulfur dioxide is ALWAYS the same. The
  subscripts are there to tell us how many of each
  atom we need to make a molecule of a compound.
  SUBSCRIPTS do not change. The recipe for water is
  ALWAYS the same.
• SO
• When you go to balance chemical equations you may
  NEVER NEVER EVER NEVER change a subscript in
  order to balance a chemical equation.

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We will now practice balancing a LOT of chemical
reaction.

• It is like solving a puzzle.
• Some of you will do well, others of you will
  struggle.
• There are no hard and fast rules except
  ONEwhatever is on the left of the equation must
  equal whatever is on the right.
• So when you ask Miss Malley, is this right? I
  will answer count!!! Just count!!!
• Lets try some.

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There are 5 common types of Chemical reactions.

• 1. Synthesis reaction.
• From simple to complex.
• AB AB Two simple reactants, substances, join
  together to seek stability at the OEL e-. The
  product is a more complex compound.
• 2. Analytical reaction. When your English teacher
  asks you to analyze a poem, what do you do? Dont
  you take it apart and look at it line by line,
  word by wordsee what its made of? So Analysis
  is to take apart, look at what is is made of.
• So in chemistry we start with a complex compound
  and tear it apart, down to its simpler building
  blocks.
• AB AB

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Single replacement reactions

• 3. The third type of chemical reaction is just
  thisa single replacement reaction.
• A BC AC B
• Bill and Cynthia go to the dance. Antonio goes to
  the dance aloneuh oh,
• Poor Bill has been replaced by AntonioAntonio is
  taking Cynthia home.
• One element replaces another element in a
  compound.
• We start out with a compound and a free standing
  element. We end up with a different compound and
  a different free standing element.
• AB C CB A

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Double replacement reaction

• 4. Double replacement reactions look the most
  complicated.
• Reactants are two compounds, products are two
  different compounds.
• Two couples go to a dance and everyone changes
  partners.
• AB CD AD CB

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Combustion reaction

• 5. The 5th chemical reaction is combustion which
  means burning.
• It is EASY to spot because the products are
  always the same.
• We start with some Hydrocarbon compound we add
  oxygen and the products are always carbon dioxide
  and water!
• Miss Malley will now give you a lot of examples
  for you to identify.

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A few more terms to know

• In chemical reactions there is always some energy
  echange involved, absorbed or given off.
• There is something called activation energy. That
  is the energy needed to start a chemical
  reaction, give the reactants a nudge to get them
  started.
• A push on the sled. A push to start a skateboard.
  A match to light a fire.
• A CATALYST is a substance often used in chemical
  reactions. A catalyst is a substance that speeds
  up a chemical reaction but does not get involved
  directly. Your friend fixes you up with someone
  but your friend does not go the date! Your
  friend brings two people together and then steps
  back. So thats what a catalyst does in a
  chemical reaction. Speeds up the reaction but in
  the end is not PART of the reactants.
• Enzymes are excellent examples of catalysts. In
  the human body thats the job of an enzyme to
  speed up reactions, let them take place at a
  relatively low temperature98.6F is not a very
  high temperaturewe cook roasts at 350F. Body
  temperature cannot be too high since
  proteinslike your brainstarts to unravel at
  higher temps. So catalysts are REALLY essential
  in surviving.

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A huge topic!!

• There is lots of work to be done. Worksheets,
  videos, projects, quizzes, tests all ongoing and
  upcoming.
• You will be asked to memorize material.