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Investigating Atoms and Atomic Theory - Download as PowerPoint

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									        Kentucky Core Content
   SC-08-1.1.1
   Students will:
   interpret models/representations of
    elements;
   classify elements based upon patterns in
    their physical (e.g., density, boiling point,
    solubility) and chemical (e.g., flammability,
    reactivity) properties.
            Core Content Cont.
   SC-08-1.1.2
   Students will understand that matter is made of
    minute particles called atoms, and atoms are
    composed of even smaller components. The
    components of an atom have measurable
    properties such as mass and electrical charge.
    Each atom has a positively charged nucleus
    surrounded by negatively charged electrons.
    The electric force between the nucleus and the
    electrons holds the atom together.
        Core Content Cont.
 SC-08-1.1.3
 Students will understand that the atom’s
  nucleus is composed of protons and
  neutrons that are much more massive
  than electrons.
          Investigating Atoms and Atomic Theory


   Students should be able to:
     Describe the particle theory of matter.
     Use the Bohr model to differentiate among the
      three basic particles in the atom (proton,
      neutron, and electron) and their charges,
      relative masses, and locations.
     Compare the Bohr atomic model to the
      electron cloud model with respect to their
      ability to represent accurately the structure of
      the atom.
               Journal 3-16-2010
Why do physicists study
particles?
Physicists study particles
because everything is made
of them, including us! People
have been trying to
understand what the Universe
is made of forever. One of the
earliest theories said that
everything could be built from
just four elements, Earth, Air,
Fire and Water. This was a
great scientific theory
because it was simple. But it
had one big drawback: it was
wrong. WHY?
   Atomos: Not to Be Cut

The History of Atomic Theory
                         Atomic Models
   This model of the
    atom may look
    familiar to you. This is
    the Bohr model. In
    this model, the
    nucleus is orbited by
    electrons, which are
    in different energy
    levels.
       A model uses familiar ideas to
        explain unfamiliar facts
        observed in nature.
            A model can be changed as
             new information is collected.
 The atomic
 model has
 changed
 throughout the
 centuries,
 starting in 400
 BC, when it
 looked like a
 billiard ball →
          Who are these men?
In this lesson, we’ll learn
about the men whose quests
for knowledge about the
fundamental nature of the
universe helped define our
views.
                    Democritus   400 BC

   This is the Greek
    philosopher Democritus
    who began the search for
    a description of matter
    more than 2400 years
    ago.
      He asked: Could
       matter be divided into
       smaller and smaller
       pieces forever, or was
       there a limit to the
       number of times a
       piece of matter could
       be divided?
Atomos
    His theory: Matter could
     not be divided into
     smaller and smaller
     pieces forever, eventually
     the smallest possible
     piece would be obtained.
    This piece would be
     indivisible.
    He named the smallest
     piece of matter “atomos,”
     meaning “not to be cut.”
Atomos
      To Democritus, atoms
       were small, hard
       particles that were all
       made of the same
       material but were
       different shapes and
       sizes.
      Atoms were infinite in
       number, always
       moving and capable
       of joining together.
  This theory was ignored and
forgotten for more than 2000
years!
   The eminent
    philosophers
    of the time,
    Aristotle and
    Plato, had a
    more
    respected,      Aristotle and Plato favored the earth, fire, air
                    and water approach to the nature of matter.
    (and            Their ideas held sway because of their
                    eminence as philosophers. The atomos idea
    ultimately      was buried for approximately 2000 years.

    wrong)
    theory.
              Dalton’s Model
   In the early 1800s,
    the English
    Chemist John
    Dalton performed a
    number of
    experiments that
    eventually led to
    the acceptance of
    the idea of atoms.
Dalton’s Theory
          He deduced that all
           elements are composed of
           atoms. Atoms are
           indivisible and
           indestructible particles.
          Atoms of the same element
           are exactly alike.
          Atoms of different elements
           are different.
          Compounds are formed by
           the joining of atoms of two
           or more elements.
               .

 Thistheory
 became one
 of the
 foundations
 of modern
 chemistry.
Thomson’s Plum Pudding
        Model
            In1897, the
            English scientist
            J.J. Thomson
            provided the first
            hint that an atom
            is made of even
            smaller particles.
          Thomson Model
 He proposed a
  model of the atom
  that is sometimes
  called the “Plum
  Pudding” model.
 Atoms were made
  from a positively
  charged substance
  with negatively
  charged electrons
  scattered about,
  like raisins in a
  pudding.
            Thomson Model
 Thomson     studied
  the passage of
  an electric
  current through a
  gas.
 As the current
  passed through
  the gas, it gave
  off rays of
  negatively
  charged
  particles.
         Thomson Model
                    Where did
                    they come
     surprised
 This              from?

 Thomson,
 because the
 atoms of the gas
 were uncharged.
 Where had the
 negative charges
 come from?
Thomson concluded that the
negative charges came from within
the atom.

A particle smaller than an atom had
to exist.

The atom was divisible!
Thomson called the negatively
charged “corpuscles,” today known
as electrons.

Since the gas was known to be
neutral, having no charge, he
reasoned that there must be
positively charged particles in the
atom.

But he could never find them.
         Rutherford’s Gold Foil
             Experiment
   In 1908, the
    English physicist
    Ernest Rutherford
    was hard at work
    on an experiment
    that seemed to
    have little to do
    with unraveling the
    mysteries of the
    atomic structure.
 Rutherford’s experiment Involved
 firing a stream of tiny positively
 charged particles at a thin sheet of
 gold foil (2000 atoms thick)
   Most of the positively
    charged “bullets” passed
    right through the gold
    atoms in the sheet of
    gold foil without changing
    course at all.
   Some of the positively
    charged “bullets,”
    however, did bounce
    away from the gold sheet
    as if they had hit
    something solid. He
    knew that positive
    charges repel positive
    charges.
   http://chemmovies.unl.edu/ChemAnime/R
    UTHERFD/RUTHERFD.html
   This could only mean that the gold atoms in the
    sheet were mostly open space. Atoms were not
    a pudding filled with a positively charged
    material.
   Rutherford concluded that an atom had a small,
    dense, positively charged center that repelled
    his positively charged “bullets.”
   He called the center of the atom the “nucleus”
   The nucleus is tiny compared to the atom as a
    whole.
Rutherford
        Rutherford reasoned
         that all of an atom’s
         positively charged
         particles were
         contained in the
         nucleus. The
         negatively charged
         particles were
         scattered outside the
         nucleus around the
         atom’s edge.
            Bohr Model
 In1913, the
 Danish scientist
 Niels Bohr
 proposed an
 improvement. In
 his model, he
 placed each
 electron in a
 specific energy
 level.
Bohr Model
        According to
         Bohr’s atomic
         model, electrons
         move in definite
         orbits around the
         nucleus, much like
         planets circle the
         sun. These orbits,
         or energy levels,
         are located at
         certain distances
         from the nucleus.
Wave Model
The Wave Model
         Today’s atomic
          model is based on
          the principles of
          wave mechanics.
         According to the
          theory of wave
          mechanics,
          electrons do not
          move about an
          atom in a definite
          path, like the
          planets around the
          sun.
              The Wave Model
   In fact, it is impossible to determine the exact
    location of an electron. The probable location of
    an electron is based on how much energy the
    electron has.
   According to the modern atomic model, an atom
    has a small positively charged nucleus
    surrounded by a large region in which there are
    enough electrons to make an atom neutral.
                Electron Cloud:
   A space in which
    electrons are likely to be
    found.
   Electrons whirl about the
    nucleus billions of times
    in one second
   They are not moving
    around in random
    patterns.
   Location of electrons
    depends upon how much
    energy the electron has.
             Electron Cloud:

   Depending on their energy they are locked into a
    certain area in the cloud.
   Electrons with the lowest energy are found in
    the energy level closest to the nucleus
   Electrons with the highest energy are found
    in the outermost energy levels, farther from
    the nucleus.
             Indivisible Electron   Nucleus   Orbit   Electron
                                                      Cloud
Greek            X
Dalton          X
Thomson                   X
Rutherford                X           X
Bohr                      X           X        X
Wave                      X           X                   X
List 3 key points
from today’s
lesson on atomic
theory history.
       Journal 3-17-10
   Compare and contrast physical and
    chemical changes in matter.

You may use any graphic organizer you
 wish to complete this journal.
 Atomic
Structure
        Core Content for Assessment
   SC-08-1.1.3
       Students will understand that the atom’s nucleus is
        composed of protons and neutrons that are much more
        massive than electrons.
   SC-08-1.1.2
       Students will understand that matter is made of minute
        particles called atoms, and atoms are composed of even
        smaller components. The components of an atom have
        measurable properties such as mass and electrical charge.
        Each atom has a positively charged nucleus surrounded by
        negatively charged electrons. The electric force between the
        nucleus and the electrons holds the atom together.
          Structure of an atom
               (page 256 in Sciencesaurus)

   Nucleus – The core of an atom. Contains
    protons and neutrons.

   Protons – Positively (+) charged particles
    found in the nucleus of an atom.

   Neutrons – Neutrally charged particles found
    in the nucleus of an atom.

   Electrons – Negatively (-) charged particles
    found outside the nucleus of an atom.
           Structure of an atom
   Valence electron – the fartheset away or most
    loosely held electrons which help determine
    how elements bond.

   Electron Dot Diagram – A diagram in which
    each dot represents one electron in the outer
    valence “shell”. (pg 268 in Sciencesaurus)

   Isotopes – Atoms of the same element that
    have different number of neutrons (eg.
    Carbon)
                             3rd Verse:
1st Verse:
They’re tiny and they’re     Neutrons can be found,
                             Where protons hang
teeny,
                             around;
Much smaller than a beany,
                             Electrons they surround
They never can be seeny,
The Atoms Family.            The Atoms Family.
                             Chorus
Chorus
                             Chorus:
2nd Verse:
Together they make gases,    They are so small.
                             (Snap, snap)
And liquids like molasses,
                             They’re round like a ball.
And all the solid masses,
                             (Snap, snap)
The Atoms Family
                             They make up the air.
Chorus
                             They’re everywhere.
                             Can’t see them at all.
                             (Snap, snap)
They’re tiny and they’re
         teeny,
 Much smaller than a
         beany,
They never can be seeny,
  The Atoms Family.
   They are so small.
          (Snap, snap)

They’re round like a ball.
          (Snap, snap)

 They make up the air.
 They’re everywhere.
 Can’t see them at all.
          (Snap, snap)
Together they make gases,
And liquids like molasses,
 And all the solid masses,
   The Atoms Family
   They are so small.
          (Snap, snap)

They’re round like a ball.
          (Snap, snap)

 They make up the air.
 They’re everywhere.
 Can’t see them at all.
          (Snap, snap)
 Neutrons can be found,
Where protons hang around;
 Electrons they surround
   The Atoms Family.
              Journal
           March 17, 2010




    What is the name of this atom model and
who was the scientist that created it?
           Reviewing Matter
   Three principal states of matter
     Solid
     Liquid
     Gas
                  States of matter
 Solid: molecules are tightly packed together;
  definite shape and volume
 Liquid: molecules are able to move around, but
  are still bonded; no definite shape, but definite
  volume
       Viscosity: the resistance of a liquid to flowing.
          Highviscosity flows slowly
          Low viscosity flows quickly

   Gas: molecules are spread apart, filling the
    space available; no definite shape or volume
    Characteristics of matter
 Boiling point (vaporization): the temperature at
  which a liquid changes to a gas
 Melting point: the temperature at which a solid
  changes to a liquid
 Condensation point: the temperature at which a
  gas turns to a liquid (the same temperature as
  the boiling point)
 Freezing point: the temperature at which a
  liquid changes to a solid (the same temperature
  as the melting point)
        Changes in Matter
 Physicalchange: alters the form of a
 substance, but not its identity
   Examples:   mixing salt and water, freezing
   water
 Chemical change: substances combine
 or break apart to form new substances
            burning wood, heating sugar to
   Examples:
   make caramel
          Types of Matter
 Mixtures: two or more substances that
 are in the same place but are not
 chemically combined
   Examples:   Kool-aid, sea water
 Puresubstances: made of only one kind
 of matter and has definite properties.
         Pure Substances
 Elements: a substance that cannot be
 broken down into other substances by
 chemical or physical means
   Examples:   iron, copper, aluminum
 Compounds:  a substance made of two or
 more elements that are chemically
 combined
   Examples:   sugar, salt
   Clean sheet of paper
 Put   your name on the paper
 Number your page 1-22
 On the next slide, you will see a
  list of items, place a “P” next to
  the number if the change is
  physical
 Place a “C” next to the number if
  the change is chemical
1.    Glass breaking
2.    Hammering wood together to build a
      playhouse
3.    A rusting bicycle
4.    Melting butter for popcorn
5.    Glassblower creating sculptures out of glass
6.    Freezing chocolate-covered bananas
7.    Separating sand from gravel
8.    Spoiling food
9.    Burning toast
10.   Making salt water to gargle for a sore throat
11.   Mixing lemonade powder into water
12.Cream  being whipped
13.Water evaporating from a pond
14.Cutting grass
15.Burning leaves
16.Humidifier putting moisture into the air
17.Corroding metal
18.Bleaching your hair
19.Fireworks exploding
20.Squeezing oranges to get orange juice
21.Frying an egg
22.Pouring milk on your oatmeal
      Journal 3-18-10
      Hint: Look at Section L page 169


1. Describe the arrangement
   of the periodic table.
2. Explain what kind of
   information can be found
   on the periodic table?
Elements and the Periodic
         Table
     (page 265 in Sciencesaurus)
                      Core Content for
SC-08-1.1.1            Assessment
 Students will:
     interpret models/representations of elements;
     classify elements based upon patterns in their physical (e.g.,
      density, boiling point, solubility) and chemical (e.g.,
      flammability, reactivity) properties.
 Models enhance understanding that an element is composed of
  a single type of atom. Organization/interpretation of data
  illustrates that when elements are listed according to the
  number of protons, repeating patterns of physical (e.g., density,
  boiling point, solubility) and chemical properties (e.g.,
  flammability, reactivity), can be used to identify families of
  elements with similar properties.
                                                               DOK 2
Why is the Periodic Table
   important to me?
                The periodic table is
                 the most useful tool to
                 a chemist.
                You get to use it on
                 every test.
                It organizes lots of
                 information about all
                 the known elements.
Pre-Periodic Table Chemistry …

   …was a mess!!!
   No organization of
    elements.
   Imagine going to a
    grocery store with no
    organization!!
   Difficult to find
    information.
   Chemistry didn’t make
    sense.
Dmitri Mendeleev: Father of the
            Table
    HOW HIS                    SOME
    WORKED…                    PROBLEMS…
   Put elements in rows      He left blank spaces
    by increasing atomic       for what he said were
                               undiscovered
    weight.                    elements. (Turned
   Put elements in            out he was right!)
    columns by the way        He broke the pattern
    they reacted.              of increasing atomic
                               weight to keep similar
                               reacting elements
                               together.
     The Current Periodic Table
 Mendeleev wasn’t too far off.
 Now the elements are put in rows by

        ATOMIC
    increasing
    NUMBER!!
 The horizontal rows are called periods and
  are labeled from 1 to 7.
 The vertical columns are called groups are
  labeled from 1 to 18.
                        Groups
   Vertical columns of elements
    in the periodic table.
   Also known as Families.
    Families may be one column,
    or several columns put
    together.
   The elements in each group or
    family, have similar
    characteristics.
   Families have names rather
    than numbers. (Just like your
    family has a common last
    name.)
    Journal: March 22, 2010
Journal Prompt: Describe the
following terms related to the
periodic table of elements:


       Period
       Group
       Family
       Noble gases
     Groups…Here’s Where the
     Periodic Table Gets Useful!!
 Elements             in    Why??
    the same                 • They have the same
    group have                 number of valence
                               electrons.
    similar
                             • They will form the
    chemical and               same kinds of ions.
    physical
    properties!!
   (Mendeleev did that on
    purpose.)
Hydrogen
       Hydrogen belongs to a
        family of its own.
       Hydrogen is a diatomic,
        reactive gas.
       Hydrogen was involved in
        the explosion of the
        Hindenberg.
       Hydrogen is promising as
        an alternative fuel source
        for automobiles
                 Alkali Metals
   1st column on the
    periodic table (Group
    1) not including
    hydrogen.
   Very reactive metals,
    always combined with
    something else in
    nature (like in salt).
   Soft enough to cut
    with a butter knife
          Alkaline Earth Metals
   Second column on
    the periodic table.
    (Group 2)
   Reactive metals that
    are always combined
    with nonmetals in
    nature.
   Several of these
    elements are
    important mineral
    nutrients (such as Mg
    and Ca
Transition Metals

    Elements in groups
     3-12
    Less reactive harder
     metals
    Includes metals
     used in jewelry and
     construction.
    Metals used “as
     metal.”
                Boron Family
   Elements in group 13
   Aluminum metal was
    once rare and
    expensive, not a
    “disposable metal.”
Carbon Family
         Elements in group
          14
         Contains elements
          important to life and
          computers.
         Carbon is the basis
          for an entire branch
          of chemistry.
         Silicon and
          Germanium are
          important
          semiconductors.
Nitrogen Family
           Elements in group 15
           Nitrogen makes up over
            ¾ of the atmosphere.
           Nitrogen and
            phosphorus are both
            important in living
            things.
           Most of the world’s
            nitrogen is not available
            to living things.
           The red stuff on the tip
            of matches is
            phosphorus.
    Oxygen Family or Chalcogens
   Elements in group 16
   Oxygen is necessary
    for respiration.
   Many things that
    stink, contain sulfur
    (rotten eggs, garlic,
    skunks, etc.)
                     Halogens
   Elements in group 17
   Very reactive, volatile,
    diatomic, nonmetals
   Always found
    combined with other
    element in nature .
   Used as disinfectants
    and to strengthen
    teeth.
The Noble Gases
             The Noble Gases
   Elements in group 18
   VERY unreactive,
    monatomic gases
   Used in lighted “neon”
    signs
   Used in blimps to fix
    the Hindenberg
    problem.
   Have a full valence
    shell.
The Atoms Family Story
In the center of Matterville, there is a   Name:
place called the Nucleus Arcade,           Patty Proton
where two members of the Atoms
Family like to hang out. Perky Patty       Description:
Proton, like her sisters, is quite large   Positive
with a huge smile and eyes that
sparkle (+). Patty is always happy
                                           Favorite Activity:
and has a very positive personality.       Hanging out at the Nucleus
Nerdy Nelda Neutron is large like          Arcade
Patty, but she has a boring, flat          Name:
mouth and eyes with zero expression
(o). Her family is very apathetic and
                                           Nelda Neutron
neutral about everything.         Patty,   Description:
Nelda, and their sisters spend all their   Neutral
time at the arcade.
                                           Favorite Activity:
                                           Hanging out at the Nucleus
                                           Arcade
Around the Nucleus Arcade, you
will find a series of roadways that   Name:
are used by another member of the     Elliott Electron
Atoms Family, Enraged Elliott         Description:
Electron. Elliott races madly         Negative
around the Arcade on his bright       Favorite Activity:
red      chrome-plated     Harley-    Racing around the arcade
Davidson. He rides so fast that no
one can be sure where he is at any
time. Elliott is much smaller than
Patty and Nelda and he is always
angry because these bigger
relatives will not let him in the
Arcade. He has a frown on his
face, eyes that are squinted with
anger, and a very negative (-)
attitude.
The morale of Matterville is stable as long as each negative
Electron brother is balanced out by one positive Proton sister.
The number of residents in Matterville depends on the Proton
and Neutron families.

Challenge: What would happen to the morale of Matterville if
one Elliott Electron was kidnapped?
The first energy street can only
hold only two Electron brothers.
The second and third energy
streets, called the Energy Freeway,
can hold 8 brothers. The fourth
energy street, called the Energy
Superhighway, can hold 18 of the            Energy
brothers.                                   Superhighway Can
                                            hold 18 electrons
 Energy Freeway
 Can hold 8                                      Energy
 electrons                                       Freeway Can
                                                 hold 8
                                                 electrons
                                      Nucleus Arcade
 Energy Street                        Contains protons &
  Can hold 2                          neutrons
 electrons
            Valence Electrons
   Electrons that are involved in transfer or
    sharing.

   The number of valence electrons an
    element has increases from left to right
    across a period.
       Journal – 3/23/2010

Use the periodic to diagram
elements O and Li.
Remember that the electron
configuration for each
orbital is 2, 8, 8, 18.
      The Atoms Family - Atomic Math
                Challenge
                         Atomic Number
                         Symbol
                         Name
                         Atomic Mass

                                    ____________ or electrons
Atomic number equals the number ofprotons
________________.
                                  protons          neutrons
Atomic mass equals the number of ______________ + __________
Assignment: Finish the rest of the worksheet and
           turn it in to your teacher.
              “Electron Cloud”
   Electrons are arranged around the
    Nucleus in SHELLS. For simplicity they
    can be thought of like mini-planets orbiting
    a central sun, but it is closer to the truth to
    think of them as "clouds" of electric charge
    around the Nucleus.
            Electron Dot Diagrams




Examine the Electron Dot Diagram above – write at
least 3 observations about the periodic table’s
arrangement and how the arrangement compares
to the number of dots it has beside it. Use the
sciencesaurus book to help you write your
observations page 265. Read page 268 – write 2
facts
     How to write and Electron Dot Diagram
1.    Write the symbol of the element.
      (Each side of the letter represents
      an electron orbital.)
      Find the # of electrons in the


                                             C
2.
      valence shell (the outermost
      shell).
3.    The dots representing the
      electrons in the valence shell are
      placed around the symbol
      beginning with the right side of the
      letter.

								
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