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
The Search for Order
(Reasons for order)
 Brings order to seemingly unrelated
facts
 Helped chemists predict the
existence of elements that weren’t
discovered yet
 Groups elements according to their
chemical and physical properties
Mendeleev’s Periodic Table
Strategy for
organization: What
did he look at?
 chemical
properties
 physical properties
 atomic mass
 density
 color
 melting point
 valence
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/ DEF.
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
Evidence Supporting
Mendeleev’s Table
 Close
match between Mendeleev’s
predictions and the actual
properties of new elements showed
how useful table was.
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Ex. Discovery of: Aluminum, Gallium, Scandium,
and Germanium
Section 5.2
The Modern Periodic Table
Repeating patterns
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Elements in same column are related
because properties repeat in regular intervals
The Modern Periodic Table
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Listed in order of increasing number of
protons
Properties of the elements repeat.
Periodic Law- when the elements are
arranged in order of increasing number of
protons, the properties tend to repeat in a
pattern
Columns in the Periodic Table
-vertical classification or groupings
-often referred to as families or groups
-each column is numbered 1-18 or 1A
through 8A
-elements within the same family have
similar properties
Rows in the Periodic Table
-horizontal classification or groupings
-each row is called a period
-elements in a period are not alike in
properties, properties change greatly
across a given row
-the first element in a period is a very
active metal
-the last element in most periods is a
noble gas
-only seven periods
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
atomic mass
6
C
For example:
Carbon
12.01
Carbon has an atomic
number of 6 (or has 6
protons), an atomic mass
of 12.01 and a symbol of C
Atomic Mass
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Two isotopes of copper
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72% copper-63
28% copper-65
Makes the average 63.56 amu
Metals
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Majority of elements
Luster – shiny.
Ductile – drawn into thin wires.
Malleable – hammered into sheets.
Conductors of heat and electricity.
Include transition metals – “bridge” between
elements on left and 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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Have properties similar to metals and nonmetals
Can conduct heat and electricity like metals
but not as good
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
 Ion (charged atom) pattern is seen
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Section 5.3
Representative Groups
Valence electrons
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The electrons in the outermost energy level
Responsible for most of the chemical
properties
When two atoms interact, the outside
electrons are the ones affected
Elements in a group have similar properties
because they have same number of valence
electrons
Ten major families:
1. alkali metals
2. alkaline earth metals
3. transition elements
4. boron family
5. carbon family
6. nitrogen family
7. oxygen family
8. halogen family
9. noble gases
10. rare earth metals
Alkali Metals
- one electron in their outermost shell or
one valence electron
- soft, silver-white, shiny metals
- bond readily with other substances
- never found uncombined in nature
- samples must be stored in oil to keep
them from combining with water or
oxygen
- most reactive metals
- Reactivity increases down a group
Alkaline Earth Metals
- two valence electrons
- lose 2 electrons when combined
with other substances
- never found uncombined in nature
- not quite as reactive as the alkali
metals
- often mixed with other metals, such
as aluminum, to form alloys of
strong yet light in weight metals
Alkaline Earth Metals cont…
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Magnesium
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Used to make steel (lighter metal without
sacrificing strength)
Key role in photosynthesis (found in
chlorophyll)
Calcium
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Found in bones and teeth
Chalk, limestone, coral, pearls, toothpaste,
plaster
Boron Family
-have 3 valance electrons
Boron
 hard and brittle
 never found
uncombined in
nature
 found in borax
 used to make heat
resistant glass
(used in
laboratories)
5
B
Boron
10.81
Boron Family
Aluminum
 most abundant
metal in earth’s
crust
 found in a mineral
called bauxite
 extremely
important metal for
industry, light,
strong and slow to
corrode
13
Al
Aluminum
26.98
Carbon Family
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Have 4 valance electrons
Can either gain 4 electrons or
lose 4 electrons
Most compounds in the body
contain carbon
Silicon 2nd most abundant
element in Earth’s crust
Silicon used to tip saw blades
Nitrogen Family
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Have 5 valence electrons
Tend to gain 3 electrons
Nitrogen and
Phosphorous used in
fertilizers
Phosphorous used in
matches
Oxygen Family
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Have 6 valence electrons
Tend to gain 2 electrons
Oxygen most abundant
element
Sulfur used in fertilizers
Oxygen needed to for
digestion
Halogen Family
-have 7 valence electrons
-most active nonmetals
-never found free in nature
-react with the alkali metals quite
easily
-when halogens react with
metals they form compounds
called salts
-Fluorine is the most active
halogen
Halogens cont…
 Fluorine
compounds used in
toothpaste
 Chlorine used to kill bacteria
 Iodine keeps thyroid gland working
properly
The Noble Gases (Inert Gases)
-normally non-reactive
-also called inert
-all elements in this family are
gases
-outermost electron shell is full
-found in small amounts in the
earth’s atmosphere (less than
1%)
Other Areas
 Transition
Metals
 Rare Earth Elements
Lanthanide series
 Actinide Series
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