Transcript Chemistry Chapter 3 - Adams County/Ohio Valley School District

Chemistry Chapter 3
Introduction to the Periodic Table
What do the following have in common?
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The sun rising daily.
The Seasons
Your Birthday
Ringing of the bells
Halley’s Comet
A pendulum swing
The earth turning
The moon phases
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Periodic – 24 hours
Periodic – S,F,W,Sp
Periodic – every year
Periodic – each 45min
Periodic - 76 years
Periodic – back –forth
Periodic – 24 hours
Periodic – once/month
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The Search for a Periodic Table
• By 1860, 60 elements
had been found and
their atomic masses
measured.
• Some behaved in a
similar way
• Some groups behaved
different than others
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• Scientists wanted a
means to organize this
information
• Dobereiner came up
with a way to relate
the elements to predict
properties of new
elements
• Called these TRIADS
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The Halogen Triad
Chlorine
35.5 u
.00321g/
ml
-101oC
-34oC
Bromine
79.9 u
3.12 g/ml
-7oC
59oC
Iodine
127 u
4.93g/ml
114oC
185oC
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Predicting the Properties of
Mystery Elements
• Mini Lab on Page 89
• Make a table that has the information given
in #2. (Symbol, Density, melting point in K,
atomic radius in pm.) for each element
given, Si,As,Sn,Ga,Br,Te
• Work in groups of “2” for this mini lab.
• Look at page 817 for actual values.
• LET’S TALK ABOUT WHAT YOU DID!
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Mendeleev’s Periodic Table
• Russian chemist, Dmitri Mendeleev arranged the
known elements by increasing atomic mass. (see
page 88) 1869.
• He arranged elements in rows based on similar
properties (same as today)
• He found some placements by similar properties
did not go along with his atomic mass rule, but it
turned out to be correct.
• This is PERIODICITY or to repeat at regular
intervals.
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The Modern Periodic Table
• When elements have similar properties and
the atomic mass doesn’t put them in the
correct rows, atomic Number (# of Protons)
does work.
• The Modern table has the elements listed by
increasing atomic number.
• Orderly progression from metal through
noble gases, and then repeats.
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The Periodic Law
• The physical and chemical
properties of the elements repeat in
a regular pattern when they are
arranged in order of increasing
atomic number.
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Using the Periodic Table
• Relationship of elements on the periodic
table.
• Group – sometimes called a family, vertical
column
• Period – Horizontal row that makes up a
complete progression through the chemical
properties.
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Trends in reactivity within
Groups
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Work in groups of threes.
Don’t handle the Ca, use forceps.
Follow the direction in #3 carefully.
Write the answers to the two Analysis
questions in your notebook.
• Do you see any pattern in the reactivity of
metals and nonmetals?
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Atomic Structure Within a Period
• Periods start with a group 1 element and
end with a noble gas.
• The noble gases have full outer shells and
are unreactive.
• Each period moves though elements that
have one more valence electron than the
preceding element.
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Atomic Structure Within a Group
• The members of a group (elements in columns top
to bottom) have the same number of valence
electrons as other elements in that group.
• The Group Number is directly related to the
number of valence electrons. 1 and 2 have 1 and 2
electrons respectively. 13-18 have the same
number of electrons as the second digit in the
group number. So group 13 elements have 3 and
so on up through 18 who’s elements have 8.
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The Periodic Table of the
Elements
• Lab page 100-101 (THINK!)
• Make sure you understand what the
problem is and what it is you are trying to
find out.
• Make sure you write down all observations
for all the elements you are testing.
• Make sure your battery lights the light
before you try to use it for testing.
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This is a List of the Elements that
you will be testing
• In the test tubes
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• In the dishes
Oxygen (get from me)
Aluminum
Sulfur
Lead
Tin
Iodine
Magnesium
Carbon
Calcium
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Carbon
Magnesium
Aluminum
Sulfur
Tin
Bismuth
Zinc
Gallium
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Prepare the Data Table Before
You Begin Your Experiment
• List the elements you are using NOT the
ones in the book
• Make sure you look very carefully at the
appearance.
• When you use the “hammer” only hit hard
enough to see a “dent” or break off a piece
• MAKE SURE YOUR LIGHT WORKS!
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Physical States and Classes of
the Elements
• Interactive Periodic Chart
• Use this chart to find the location
of metals, nonmetal and
metalloids on the periodic chart.
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Classifying Elements
• Elements are grouped in these groups
based on their physical and chemical
properties.
• Knowing this can help you predict
what might happen with a particular
element.
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Metals
• Have Luster (metallic luster, shine as a
metal)
• Conduct heat and electricity
• Malleable and ductile
• Solid at room temperature (except Hg)
• Main group elements are fairly predictable,
transition metals are no so predictable.
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Nonmetals
• Poor conductors of heat and electricity
• May be solids, liquids or gases, if solid,
may be hard or soft, but usually brittle
• Except for C, nonmetals have 5 to 8 valence
electrons that are tightly held
• Most are gasses, but if they are solid, they
lack the metallic luster of metals ( usually
dull, earthy)
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Metalloids
• These elements may exhibit the properties
of metals or of nonmetals
• Their properties can be combination of
metal and nonmetal-like characteristics
• Some are semi-conductors (Ge, Si, As)
• The semi-conductors are “doped” with other
elements to make n and p type semiconductors.
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Atomic Structure of Metals,
Metalloids, and Nonmetals
• The way the electrons are held help
determine metallic or nonmetallic properties
• The nonmetals hold electrons tightly
• The metals hold them loosely which is the
reason they are good conductors of heat and
electricity.
• In chemical reactions, metals tend to loose
outer electrons and nonmetals gain them.
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Semiconductors and Their Uses
• Electrons and Electricity –
• See page 111-112 for Si doped with
Phosphorus or Boron
• P gives the Si and extra electron and is
called an n-type semiconductor
• B leaves a hole and is called a p-type
semiconductor
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Diodes
• Diodes are made by combining n and p type
semiconductors
• Transistors are made by sandwiching p and
n type conductors (npn and pnp are two
types)
• They are used in all kinds of electronic
devices.
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