Transcript Periodic Table

Periodic Table
History
• Antoine Lavoisier – Father of Modern
Chemistry
• 1829 German J. W. Dobereiner Grouped
elements into triads
– Three elements with similar properties
– Properties followed a pattern
– The same element was in the middle of all trends
• Not all elements had triads
Law of Octaves
• 1862 John Newlands developed Law of
Octaves
• The elements showed a repetition in their
chemical properties after 8 elements
• Used Atomic Weights but not actual values
• Important because showed the first pattern of
repeating properties
Julius Lothar Meyer
• Meyer first table published 1864 containing 28
elements
• Arranged in order of Atomic Weight and made
a clear horizontal relationship
• Allowed properties (valency) to outweigh
Atomic Weight
• Anticipated Mendeleev by years
Meyer
• Left gaps to denote unknown elements
• Not willing to make predicitions
• More focused on Physical properties not
chemical properties
• Bitter battle with Mendeleev
• Lost to Mendeleev because of Mendeleev’s
forceful ways
History
• Russian scientist Dmitri Mendeleev taught
chemistry in terms of properties
• Mid 1800 – atomic masses of elements were
known
• Wrote down the elements in order of
increasing mass
• Found a pattern of repeating properties
• Not first to develop system but his version had
the strongest impact
Mendeleev’s Table
• Grouped elements in columns by similar
properties in order of increasing atomic mass
• Found some inconsistencies - felt that the
properties were more important than the
mass, so switched order.
• Found some gaps
• Must be undiscovered elements
• Predicted their properties before they were
found
Dmitri Mendeleyev
• Mendeleyev was known as the “Father of the
Periodic Table”
• DOB: 1834-1907
• Created the first table on 3-1-1869
• Table had 70 elements
• Used properties to set up table
Mendeleev
• Distinguished from competitors by a devotion
to, and love for, the individuality of the
elements that went hand in hand with an
intimate knowledge of their chemical
characteristics
• Focused on both physical and chemical
properties
Mendeleyev Cont.
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Properties Used:
Atomic Weight
Melting Pts.
Densites
He could only predict these properties
His work preceded chemical advances by 30 years
Produced his table 27 years before the first
subatomic particle, the electron was discovered
Did not predict Noble Gases
Acceptance
• Mendeleev’s table received real acceptance in
1875
• Discovery of Scandium, Germanium and
Gallium showed Mendeleev’s predictions
were correct.
“The elements were not being arranged to make
a periodic table, but to fit the periodic table”
Meyer vs. Mendeleyev
• Julius Meyer (18301895)
• Created a table that
plotted:
• Atomic Volume vs.
Atomic Weight
• Lost out to Mendeleyev
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Published before Meyer
Final Table:
Atomic Weight vs. Valency
Table had 8 columns but
was missing Noble Gases
• Discovered 30 years later
Modern Russian Table
Spiral Periodic Table
Changing of Table
• Henry Moseley (1887-1915) – changed table
in 1913 by increasing atomic number
• Currently use this today
• Glenn Seaborg – rare earth series from
Actinium (89) up.
• Minor Changes – inner transitional Lu & Lr
replaced La & Ac
• Bohr first linked Quantum Theory
Today’s Table
More History
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First Elements Discovered:
Carbon
Sulfur
Copper
Gold & Silver
Iron
Tin
Antimony
Mercury
Lead
Oxygen (1772)
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First Classified Groups:
Gases
Non-Metals
Metals
Earths
• The elements in the A groups are
called the representative elements
1A
2A
3A 4A 5A 6A 7A
8A0
Transition metals
• The Group B
elements
VIIIB
IIB
VIIB
VIB
VB
13 14 15 16 17
3A 4A 5A 6A 7A
IB
VIIIA
VIIA
VIA
VA
IVA
IIIA
IIIB
1 2
1A 2A
IVB
IIA
IA
Other Systems
3 4 5 6 7 8 9 10 11 12
3B 4B 5B 6B 7B 8B 8B 8B 1B 2B
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8A
Vertical Columns
• Known as Groups or a Family
• Elements in same group have similar physical
& chemical properties
• Each group is identified by a group number
and group letter
• Horizontal rows are called periods
• There are 7 periods
• Group 1A are the alkali metals
• Group 2A are the alkaline earth metals
• Group 7A is called the Halogens
• Group 8 are the noble gases
The group B are called the
transition elements
 These
are called the inner
transition elements and they
belong here
Metals
Metals & Their Properties
• Metals are good conductors of heat and
electricity
• Metals are malleable
• Metals have high luster
Example of Metals
• Copper is a relatively soft metal and a very good
electrical conductor
• Mercury is the only metal that exists as a liquid at
room temperature
Non-metals
Nonmetals & Their Properties
• Carbon, the graphite in a pencil is an
example of a nonmetallic elements
• Nonmetals are poor conductors of
electricity
• Can be brittle
• Non-lustrous
• Many are gases at room temperature
Example of Nonmetals
• Sulfur was once known as Brimstone
• Microspheres of phosphorus, a reactive
nonmetal
Metalloids or Semimetals
• Properties of both
• Semiconductors
Example of a Metalloid
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Silicon is a metalloid
Silicon is brittle like a nonmetal
Silicon has metallic luster
Silicon is a semiconductor of electricity