Chapter 17 Classification of Matter

Document Sample
Chapter 17 Classification of Matter Powered By Docstoc
					  Chapter 17
Classification of
    Matter
•Everything in life can
 be put into some form
 of a classification.
 Think of your room (ok,
 not the messy ones!)
 There is a place for
 books, clothes, sports,
•Stuff, music stuff, etc.
 Classifying objects into
 broad groups makes
 things easier to find,
 identify, look at, and to
 learn about.
• Classification of
  matter is based
  on the makeup of
  matter
• According to makeup,
  matter exists as
  elements,
  compounds, mixtures
  or solutions.
•A mixture is a
 combination of two or
 more substances that
 are not chemically
 combined.
•Each substance has its
 own specific properties
 and is the same
 throughout the entire
 mixture. Ex. Pg 88-
 granite rock is made up
 of quartz, mica and
•Feldspar. Sand has
 dark specks and light
 specks when you pick
 up a handful of sand.
Properties of Mixtures
• Substances in a
  mixture are not
  chemically combined.
  They keep their
  separate identities
  and most of their own
• properties. Ex. You can
  easily taste the difference
  be/w a sugar-water
  mixture and plain water
  even though they will look
  exactly the same be/c
  sugar keeps the identity of
  sweetness.
•Substances in a
 mixture may change
 physical appearance
 when they dissolve
• (89) Subs. in a
  mixture can be
  present in any amount
• Ex. Cereal in morning
  is not in equal amts in
  the bowl.
•Subs. in a mixture can
 be separated by
 physical means. Ex.
 Salt and water. (pg 89
 in book ex-iron and
 sulpher)
• (90)Mixtures are
  classified by how
  well they are
  mixed. Ex. Compare
 stainless steel and
 concrete. Which is
•Types of
 Mixtures:
• A heterogeneous
  mixture (91)is a
  mix that does not
  appear the same
  throughout.
•It is easy to see
 because the
 particles are large
 enough. Ex. Sand,
dirt, pizza
•They are considered
 to be the “least mixed”
 of all. The particles
 are easy to separate
 from the mixture. Ex.
 Concrete.
• The particles usually settle
  out easily. Ex. Shake a jar
 of water and pebbles together
 and quickly the pebbles will
 fall to the bottom. Oil and
 water separate in dressings.
• Colloid- a
  heterogeneous
  mix with larger
  particles that
  never settle
  out(91).
• Warning: you will see
  colloids listed as
  homogenous mixtures
  also-visually they look like
  homogenous mixtures but
  microscopically they are
  heterogeneous mixtures.
• They (the particles)
  scatter light in the
  Tyndall effect, which is
  the scattering of light by
  minute particles in its
  path, such as dust in the
  air. Hence, the mixture
  appears cloudy.
• Ex. Of colloids:
• Milk, whipped cream,
  toothpaste, suntan lotion,
  fog, smoke, foam.
Suspension - a
heterogeneous
mixture containing a
liquid in which the
visible particles
settle.
       Example
•Italian Dressing or
 muddy water
•A homogeneous
 mixture is a mixture
 that appears to be
 the same
 throughout.
•The particles that
 make up this type of
 mixture are small and
 not easy to see. It is
 “well-mixed”. Ex.
 Stainless stell, you can’t see
 the chromium verses the
 iron in it.
• The particles do not settle
out when allowed to stand.
• Solutions- (92) a type of
  homogenous mixture of
  two or more substances in
  a single physical state.
• It is considered the “best-
  mixed” of all mixtures and
  is formed when one
•Substance dissolves in
 another. Ex. Ocean water,
 lemonade, and iced tea from
 a powdered mix as long as
 they are all totally dissolved.
 The air in the room is a
 solution of oxygen and other
 gases dissolved in nitrogen.
A solution always has
• Solvent-the subs that
  does the dissolving; its
  the greater amount. Ex.
  The water in the
  lemonade.
• A solution always has a
  solute -the substance that
  gets dissolved; the lesser
  amount. Ex. The
  lemonade mix itself.
• solutions look the
  same throughout b/c
  the particles are
  evenly spread. Most
  liquid solutions can
  be easily separated
  by simple physical
•Means like evaporation
 but solid solutions like
 alloys are much harder
 to separate.
•Types of solutions:
• (93-4)
• There are seven types of
  solutions that are
  possible.
Solute   Solvent    Example
 Gas      Gas          Air
 Gas     Liquid    Soda Water
 Gas      Solid     Charcoal
                    gas mask
Liquid   Liquid     Antifreeze
Liquid   Solid     Dental filling
Solid    Liquid      Ocean
                      Water
Solid     Solid    Gold jewelry
•A subs that
 dissolves in another
 is said to be soluble
•A substhat does not
 dissolve is said to
 be insoluble
• Water is known as the
  universal solvent.
• As temperature increases
  so does solubility
• Metal solutions are called
  alloys. Ex. Brass
Pure Substances (96) they
Can either be an element or
a compound (2 pure
substances together. )
• --A sample taken from any
  pure substance is identical
  to any other sample of the
  same type of pure sample.
  A sample of iron is the
  same no matter where
  you get it from.
• Ex. Iron, aluminum, pure
  water, sugar, and table
  salt will be the same
  throughout no matter
  where you find it in the
  world!
Elements—a pure
substance that is
made up of only
one kind of material
and has definite
properties
• Elements are the
  simplest pure
  substances.
• An element can not
  be changed into a
  simpler substance.
• The smallest part
  of an element is an
  atom.
• An atom is a
  building block of
  matter.
• Atoms of diff.
  elements are
  different.
• An element of iron is
  different than
  aluminum.
 Compounds (99)
A pure substance that
 is made up of more
 than one element
 and the elements are
 chemically combined
 in a fixed ratio.
• Ex’s: sugar is a compound
  made up of the elements
  carbon, hydrogen, and
  oxygen. Other
  compounds are carbon
  dioxide, ammonia, and
  baking soda.
• (100) Compounds can
  be broken down into
  simpler substances
  sometimes by a
  physical means, but
  sometimes it may take
  electrical energy.
•The properties of the
 elements that make
 up a compound are
 different from the
 properties of the
 compound.
•Would you really
 sprinkle a poisonous
 gas and a highly active
 metal on your french
 fries? NO WAY- but
 basically you do with
 table salt!
• Ex. Na (soduim) is a silvery
  metal that explodes if
  placed in water and Cl
  (cholrine) is a yellow-green
  gas that is poisonous. But
  when chemically combined
  they produce a new sub
  that’s safe to eat called salt
• (101)Most comps are
  made up of molecules,
  which is made up of
  two or more atoms
  chemically bonded
  together.
•A molecule is the
 smallest part of a
 compound that has
 the properties of
 that compound.
•Water is a compound.
 A molecule of water is
 made up of 2 atoms of
 hydrogen chemically
 bonded to 1 atom of
 oxygen.
• Just like all the atoms of
  a certain element are
  alike, all molecules of a
•Diatomic elements: (not
 in book) In nature some
 elements exists as a
 molecule. For ex. O
 (oxygen) really is only
 found with two atoms
 bonded together so it’s
•formula is O2
•The diatomic elements
 are Oxygen (O2),
 hydrogen (H2), Iodine
 (I2), Bromine (Br2),
 Fluorine (Fl2), chlorine
 (Cl2), nitrogen (N2)
•Chemical symbols (98)
 are a shorthand way of
 representing the
 elements
•(See list of
symbols and
elements) pgs.
142-143
• If the symbol has two
  letters, capitalize the
  first letter of the
  symbol.
• If the symbol has one
  letter, capitalize it
•They are representative
 of the element’s name,
 the person who
 discovered the element
 or its Latin name.
•Chemical formulas:
 (101) Chemical symbols
 are like the letters of the
 chemical alphabet. Just
 as you put letters
 together to make words,
 chemical symbols can
•be put together to make
 chemical “words”.
•1. combinations of chem
 sym are called chemical
 formulas. Chemical
 formulas are a
 shorthand way of
•representing chemical
 substances. Ex. NaCl
 or H2O
•2. (102) Subscripts are
 a numerical
 representation that
 represents how many
•atoms of that element
 are present. Subscripts
 are written to the lower
 right of the chemical
 symbol. Ex. Ammonia is a
 compound made of the
 elements nitrogen (N) and
• Hydrogen (H). The chemical
  formula for ammonia is NH3.
• A molecule of ammonia
  contains 1 atom of nitogen
  and 3 atoms of hydrogen.
• The (3) behind the NH is the
  subscript!
•3. No subscript is used
 when there is only 1
 atom of an element. In
 the example above
 there was only 1
 nitrogen atom so you do
 not see 1 as a subscript.
•4. A coefficient (104) is
 written to tell you how
 many whole units of that
 substance are present.
•2 NaCl -means there are
 two molecules Each
 containing 1 atom of Na and 1
 atom of Cl
•Ex.s- (not on handout)
  PO2Mg3
• # of units= 1
• Elements & # of atoms:
  potassium has 1 atom, oxygen
  has 2 atoms, magnesium has 3
  atoms.
•3Ag2N3O2=
•3 units total
•6 silver atoms total
•9 nitrogen atoms total
•6 oxygen atoms total
•Now work the ones on
 your handout.
•Chemical equations:
 (102-3) If chem sym’s
 are letters and chemical
 formulas are the words,
 then we must be able to
 write chemical
 sentences.
•A chem sentence is a
 way to describe a
 chemical equation.
•It describes how atoms
 of one substance are
 chemically changed into
 atoms of a whole new
•Substance with totally
 different properties.
 (remember how Na Cl combine to
 make something you can ingest?)
•Ex.
•C + O2      CO2

 reactants    products
• Carbon + Oxygen yields
  (produces) carbon dioxide
•The right side of the
 chemical equation are
 the products and the left
 side are the reactants.
 The arrow means yields
 are produces.
•Balanced equations:
 (104)
•The Law of
 Conservation of
 Mass/Matter and the
 The Law of
 Conservation of Energy
•states that neither of
 these (mass nor energy)
 can ever be created or
 destroyed. They can
 only be conserved.
•The chemical equation
 is basically explaining to
 you what things went
 into the reaction and
 how did they combine,
 or the opposite, what
 went into the reaction
•and how did it
 chemically break apart.
•The key to an equation
 being written correctly is
 that the formulas on
 each side must always
 show that they are equal
•Amounts of mass on
 both sides of the yield
 sign because of the law
 of conservation of mass!
•To balance an equation
 remember this: YOU
 MAY NEVER CHANGE
•A SUBSCRIPT, YOU
 CAN ONLY CHANGE A
 COEFFICIENT!!!!!
•The total amount of
 atoms present on the
 reactant side of
 equation must match
•the total number of
 atoms on the product
 side of the equation.

•Now let’s try some basic
 balancing!!

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:8
posted:9/25/2012
language:English
pages:86