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Identify material as pure substance or mixture given

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Identify material as pure substance or mixture given Powered By Docstoc
					       2nd 6 weeks review
• Please have a seat
• Remember NO FOOD, NO DRINKS, NO
  GUM!
• THANKS FOR YOUR COOPERATION…
 2.1b Identify a material as a pure substance or a mixture, given a
                      description of the material
 2.1c Distinguish among elements, compounds, solutions, colloids,
                  and suspensions, given examples
2.2c Identify the three major subatomic particles (protons, neutrons,
 and electrons) based on their locations, charge and relative mass,
                         given descriptions.
 2.3a Identify the atomic number, atomic mass, number of protons,
number of neutrons, and number of electrons in an atom of a given
                   element, using the periodic table.
  2.2bDistinguish between metals and nonmetals, given examples.
2.2d Identify chemical formulas for common compounds (i.e. H2O,
            NaCl, CO2, HCl, Fe2O3, C6H12O6, NaOH).
 3.2e Distinguish between an endothermic or exothermic reaction,
           given a description of the temperature change.
                 Matter
• Pure substance is made of only one
  kind of material and has definite
  properties. All the particles are exactly
  the same. Iron, Aluminum, water,
  sugar, and table salt are examples of
  pure substances.
• Elements are the simplest pure
  substance. It cannot be changed into a
  simpler substance by heating or any
  chemical process.
Matter is divided into 3
         types:
    • Elements
    • Compounds
    • Mixtures
            Elements
• Cannot be changed by
     chemical means.
• Composed of atoms that
     are alike.
• Chemical Symbols are a short-
  ha n d w a y o f r e p r e s e n t i n g
  elements
• Each element has its
     own square on the
     periodic table.
    Compounds
• Can be changed by
   chemical reactions.
• Composed of two or
   more elements
   chemically combined
• Molecules are the
   smallest compound
   particles.
       Compounds
• Compounds are represente
  d by combinations of
    chemical symbols with
    subscripts indicating the
    number of atoms of each
    element.
                        NH4NO3
                C6H12O6
       H2SO4
             NaCl        H2O
                 Matter
• Matter is classified as a mixture if each
  part of the matter has its own
  properties. The parts of a mixture need
  have no certain ratio to each other.
  Clothing, food, salad dressing and soft
  drinks are examples of mixtures.
• In a homogeneous mixture the
  substances are spread evenly
  throughout.
                Matter
• A heterogeneous mixture is not the
  same throughout. The particles are
  large enough to be seen and will settle
  when left alone. Sand in water, italian
  salad dressing, trail mix are examples.
                 Matter
• The particles in a homogeneous mixture
  do not settle when allowed to stand.
  Stainless steel, milk, toothpaste, lotion
  are examples.
                Matter
• A homogeneous mixture of two or more
  liquids that are able to dissolve into
  each other in various proportions is
  called miscible. Water and rubbing
  alcohol dissolve into each other.
• In the heterogeneous mixture of two or
  more liquids that do not mix into each
  other is called immiscible. Mixing oil
  and water is an example.
• Miscibility only refers to the mixing of
  liquids.
          History of the atom
• D e m o c r i t u s- 400 B.C. “atomos”
• Dalton- 1803; First model of atomic theory
• J.J. Thomson- 1897; discovered electron
• Rutherford- 1908; positive nucleus
• Bohr- 1913; planetary model (because the
  energy levels the electrons travel in surround
  the nucleus and look like rings of a planet)
• Wave Model (Electron cloud)- 1926; electrons
  travel in random energy levels.
Atomic models
 1.All matter is composed of
   extremely small particles
   called atoms


2. Atoms of a given element
   are identical in size, mass,      ELEMENT
   and other properties; atoms          2
   of different elements differ in   ELEMENT
   size, mass, & other                  3
   properties                        ELEMENT
                                         4

Atomic Theory
 3. Atoms cannot be
    subdivided, created,
    or destroyed

 4. In chemical rxns,
   atoms are combined,       +             +
   separated, or
   rearranged
                           Reactants   Products




Atomic Theory
                       Outer
 electron   e-   -1    energy
                       shells
                                9.11x10-28

  proton    p+   +1   nucleus   1.67x10-24

  neutron n0    0    nucleus 1.67x10-24

Structure of the Atom
Location of Subatomic Particles
             10-13 cm

electrons


                         protons
              nucleus

                        neutrons



             10-8 cm
Design of the Periodic Table

• Atoms of most metals have four or
  fewer electrons in their outer energy
  level.
• Metals are shiny, conduct heat and
  electricity well, high density, high
  melting points.
• Metals tend to lose electrons when they
  react.
  Design of the Periodic Table

• Because of their electron arrangement,
  metals are:
  – Ductile – able to be drawn into a wire
  – Malleable – able to be hammered and
    flattened into sheets.
• Elements on the right side of the table are
  nonmetals.
• Nonmetals usually have five or more
  electrons in their outer shell.
  Design of the Periodic Table

• Nonmetals usually have no luster and are
  dull, they do not conduct heat and
  electricity well, and they are brittle (break
  easily).
• They are neither ductile or malleable.
• Nonmetals are noticeably different from
  one another.
• Nonmetals have 5 or more electrons in
  their outer level.
  Design of the Periodic Table

• Nonmetals tend to gain electrons.
• Metalloids have properties of both metals
  and nonmetals.
• They conduct heat and electricity, are
  ductile and malleable, and can be either
  shiny or dull.
• Transition elements make up groups 3 –
  12. Elements in these groups have 1, 2,
  or 3 valence electrons.
Alkali Metals


Soft, silvery colored
metals
Very reactive!!!
Elements of this group
have 1 valence electron
Alkali Metals reacting with water:

    •   Li (Lithium)
    •   Na (Sodium)
    •   K (Potassium)
    •   Rb (Rubidium)
    •   Cs (Cesium)
               What would you expect
               from Francium?!?!
  Alkaline Earth Metals

Silvery-White Metals
Fairly reactive
Many are found in rocks in
the earth’s crust
Elements in this group
have 2 valence electrons
Transition Metals




Most are good       Malleable (easily
Conductors of       bent/hammered into
electricity         wires or sheets)
 Metalloids lie on
 either side of these
 “stairsteps”


They share properties with
both metals and non-metals
Si (Silicon) and Ge
(Germanium) are very
important “semi-conductors”
    Nonmetals



Brittle
Do not conduct
electricity
 Halogens
 (salt formers)

Most are
Poisonous
Fairly reactive
Elements in this
group have 7
valence
electrons
     Noble Gases



Unreactive
Gases at room
temperature
Lanthanide Series
                    Actinide Series
       C. Molecular Nomenclature

    • The Seven Diatomic Elements
           Br2 I2 N2 Cl2 H2 O2 F2
H
                                    N O F
                                       Cl
                                       Br
                                        I
Identify the number of atoms in the
  following common compounds
•   H2O
•   NaCl
•   CO2
•   HCl
•   Fe2O3
•   C6H12O6
•   NaOH
•   H2SO4
        or Na-23                or Na-24

Isotope: one of two or more atoms having
         the same number of protons but
         different numbers of neutrons
An atom with positive or negative charge
             is called an
                                   drum roll




         ION
  WHEN REMOVING ELECTRONS
THE RESULTING CHARGE IS POSITIVE




     neutral           1+
  WHEN ADDING ELECTRONS
THE RESULTING CHARGE IS NEGATIVE




     neutral           2
-attractive force between
atoms or ions that binds
them together as a unit
-Electrons are
responsible for the type,
strength, and size of a
chemical bond
           Ionic Bonding
• The atom that gains electrons becomes
  a negatively charged ion. The atom that
  loses electrons becomes a positively
  charged ion.
• Ionization energy is low for atoms with
  few electrons and high for atoms with
  many electrons.
• Occurs between and metal and a
  nonmetal (ex. NaCl)
          Covalent Bonding
• Bonding where electrons are shared
  rather than transferred is called
  covalent bonding.
• By sharing electrons each atom fills up
  its outermost energy level at the same
  time.
• Covalent bonds occur between non-
  metals and non-metals. (ex. SiO2)
         Polyatomic Ions
• Polyatomic ions are groups of
  covalently bonded atoms that act
  like a single atom when combining
  with other atoms.
• The bond within the polyatomic ion
  are covalent – they usually form
  ionic bonds with other atoms. (ex.
  NH4Cl
         Metallic Bonds
• Metallic bonds are made of one
  metal element. There are no other
  atoms to accept the electrons the
  metal easily gives up.
• They share many electrons.
• This sharing of many electrons
  give metals its properties
  (malleable, ductile)
    EXOTHERMIC & ENDOTHERMIC REACTIONS

Exothermic process: a change (e.g. a chemical reaction)
 that releases heat. Heat moves from reactants to the
                     surroundings


A release of heat corresponds to a decrease in enthalpy




             Burning fossil
               fuels is an
              exothermic
                reaction
   Endothermic process: a change (e.g. a chemical
reaction) that requires (or absorbs) heat. Heat moves
     from the surroundings in to the reactants.


An input of heat corresponds to an increase in enthalpy




                                           Forming Na+
 Photosynthesis is an                      and Cl- ions
endothermic reaction                     from NaCl is an
(requires energy input                    endothermic
  from sun known as                          process
     light energy)
           Measuring Heat


                  Exothermic reaction, heat
                  given off & temperature of
reaction
                          water rises




                 Endothermic reaction, heat
                 taken in & temperature of
reaction
                        water drops

				
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posted:8/15/2011
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