Transcript Chapter 5: The Periodic Table

Chapter 5:
The Periodic Table
5.1 Organizing the elements
5.2 The Modern Periodic Table
5.3 Representative groups
Section 5.1
Organization of the
Elements
Search for Order
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1750 only 17 elements known
1789 Antoine Lavoisier grouped known
elements (4 groups)
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Metals
Non-metals
Gases
Earths
Next 80 years scientists looked for better
way to classify known elements
Mendeleev’s Periodic Table
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1869….Dmitri Mendeleev
(Russian teacher and
chemist) organized known
elements while playing
solitaire
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Made deck of cards with
elements
Listed name, mass and
properties
Paid attention to how
elements reacted in
chemical reactions
Mendeleev’s Periodic Table
Strategy for organization: What did he
look at?
chemical properties
 physical properties
 atomic mass
 density
 color
 melting point
 Valence electrons
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Mendeleev’s Proposal
Elements arranged in rows based on
increasing mass.
 Elements with similar properties are in
same column.
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Chart was a Periodic Table arrangement of elements in columns
based on a set of properties that repeat.
Mendeleev’s Prediction
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Table incomplete–
elements not yet
discovered
Left spaces in table for
undiscovered elements
Good models allow for
predictions to be made
based on model
Used properties of nearby
elements to predict
properties of unknown
elements
He called this element
eka-Aluminum.
Later it was renamed
Gallium after its
discovery in 1875
Evidence Supporting
Mendeleev’s Table
 Close
match between Mendeleev’s
predictions and the actual
properties of new elements showed
how useful table was.
http://www.iteachbio.com/Chemistry/Chemistry/The%20Periodic%20Ta
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Section 5.2
The Modern Periodic
Table
The Elements by Tom Lehrer
The Modern Periodic Table
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“Periodic” - Repeating patterns
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Listed in order of increasing number of
protons (atomic #)
Properties of elements repeat
Periodic Law- when elements arranged by
increasing number of protons, properties
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Columns in the Periodic Table
-vertical (up & down)
-called groups or families
-#ed 1-18 or 1A through 8A
-elements in same family have
similar properties
Rows in the Periodic Table
-horizontal (left – right)
-called periods
-properties change greatly across period
-first element in period is very active
metal
-last element in most periods is noble gas
-7 periods (number them on your
periodic table)
Element Key
Important information about an
element is given in each square
of the periodic table:
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its atomic number
chemical symbol
element name
average atomic mass
For example:
Carbon has atomic # 6
(or has 6 protons), an
average atomic mass of
12.01 and a symbol of C
6
C
Carbon
12.01
Atomic Mass
 Two
isotopes of copper
72% copper-63
28% copper-65
 Makes the average 63.56 amu
Metals
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Most solids (Hg is liquid)
Luster – shiny.
Ductile – drawn into thin
wires.
Malleable – hammered into
sheets.
Conductors of heat and
electricity.
Include transition metals –
“bridge” between elements
on left & right of table
Non-Metals
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Properties are generally opposite of
metals
Poor conductors of heat and
electricity
Low boiling points
Many are gases at room temperature
Solid, non-metals are brittle (break
easily)
Chemical properties vary
Metalloids
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stair-step pattern
Have properties similar to
metals and non-metals
Ability to conduct heat and
electricity varies with temp
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Better than non-metals but
not metals
Variation Across a Period:
Left to Right
Physical and Chemical properties
 Atomic size decreases
 Metallic properties decrease
 Ability to lose an electron decreases
 Ability to gain electrons increases
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Section 5.3
Representative Groups
Hip Hop Classroom
The Elements
What are Valence electrons?
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outermost e-’s
Responsible for chem props
Elements in same group…
same # of VE
ALL atoms want full outer
energy level (usually 8 VE)
To get full outer energy level, some
elements:
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lose e- (metals)
gain e- (non-metals)
share electrons (some non-metals & metalloids)
Introducing the
ten major
groups
(families) on the
modern
Periodic Table:
Alkali Metals
reactivity increases
- 1 valence electron (VE)
- soft, silver-white, shiny
metals
- never found pure
- most reactive metals
- Reactivity increases
down group
potassium
Label the Alkali Metals to your PT
Alkaline Earth Metals
- 2 VE
- not as reactive as
alkali metals
- often mixed with Al
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forms strong/light
weight alloys
magnesium
Alkaline Earth Metals
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Magnesium
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Used to make steel
(light metal w/o
losing strength)
photosynthesis
(chlorophyll)
Calcium
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bones & teeth
Chalk, limestone,
pearls, plaster
Label the Alkaline Earth Metals to
your PT
Boron Family
-3 VE
Boron
 Hard/brittle
 never found pure
in nature
 in borax...used to
make detergents
& cosmetics
Boron Family
Aluminum
 most
abundant
metal in
earth’s crust
 important
metal for
industry
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light, strong,
slow to
corrode
Aluminum
13
Al
Aluminum
26.98
Label the Boron Family on
your PT
silicon
Carbon Family
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4 VE
Can gain 4 e-, lose
4 e-, or share eMost compounds
in body contain C
Si 2nd most
abundant element
in Earth’s crust
Si used to tip saw
blades
Label the Carbon Family on
your PT
Nitrogen Family
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5 VE
Tend to gain 3 eN and P used in
fertilizers
P on tips of matches
Arsenic
Label the Nitrogen Family on
your PT
Oxygen Family
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6 VE
Tend to gain 2 eO very abundant element
S used in fertilizers
O needed for digestion
sulfur
Label the Oxygen Family on
your PT
Halogen Family (“salt-former”)
-7 VE
-most active nonmetals
-never found pure in nature
-react with alkali metals easily
(forms salts)
-F most active halogen
Halogens cont…
F
compounds in toothpaste
 Cl kills bacteria
 I keeps thyroid gland working
properly
bromine
Label the Halogen Group on your Periodic Table
The Noble Gases (Inert Gases)
- non-reactive
- outermost e- shell is
full (8 VE)
- In “neon” lights
-in earth’s
atmosphere (less
than 1%)
Neon
Label the Noble Gases on your Periodic Table
Transition Metals
mercury
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Almost all solids at room temp (Hg exception)
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ductile, malleable, conductors
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VE varies
Less Reactive than Groups 1 & 2
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Fe, Co, and Ni produce magnetic field
Label the Transition Metals on your periodic table
uranium
Rare Earth Elements
Lanthanide series (period 6)
 Actinide Series (period 7)
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Some radioactive
Separated from table to make easy to
read/print
silver, silvery-white, or gray metals.
Conduct electricity
Label the Lanthanide Series on
your PT
Label the Actinide Series on
your PT
You may watch more videos about the
elements at:
http://www.periodicvideos.com/
or sing along at:
http://www.youtube.com/watch?v=zGM-wSKFBpo&feature=related
elemental funkiness - Mark Rosengarten
hip hop classroom