Periodic Table
Origin of the Periodic Table
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Dmitri Mendeleev
(1869)
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http://history-ugolok.ru/mendeleev.gif 10/22/04
Developed 1st
Periodic Table
Arranged elements in
order of increasing
atomic mass
Modern Day Periodic Table

Henry Moseley (1909)
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Developed Modern
Periodic Table
Arranged elements in
order of increasing
atomic number
This allows elements
with similar
properties to be
arranged near each
other
http://mws.mcallen.isd.tenet.edu/mchi/ipc/ch06htm/images06/Moseley.jpg 10/22/04
Periodic Law
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When elements are arranged in order of
increasing atomic number, there is a
periodic repetition of their physical and
chemical properties.
Elements with similar chemical and
physical properties are in the same
column or group in the PT.
How is the modern periodic
table arranged?
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A: Increasing atomic size
B: Increasing atomic mass
C: Increasing atomic number
D: Increase atomic weight
Organization of Periodic Table
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Period
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Horizontal row
7 periods (#1-7)
Group (family)
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Vertical column
18 groups (#1-18)
Elements in a group have similar
chemical and physical properties
Periodic Table & Electron Structure
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Electron structure determines
chemical properties
Every element of a group (family) has
the same arrangement of electrons in
their outermost “shell” of the atom.
Every element has a different
number of electrons and thus
different properties.
Think back to the Bohr atom…
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Each track in the Bohr atom (n=1, n=2,
n=…) represents a new shell
Which of the following has the same
number of electrons in the outermost
shell as Br?
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A: Kr
B: Cl
C: Ca
D: Li
E: H
Four Regions of the Periodic Table
1.
2.
3.
4.
Metals
Non-metals
Metalloids
Noble gases
Regions of the Periodic Table
Noble
Gases
Adapted from: http://web.buddyproject.org/web017/web017/images/periodic%20table.JPG 10/22/04
Back
Metals
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Largest region (toward left) of periodic table
Most elements on the periodic table are metals
Solid at room temp.
Excellent conductors of heat and electricity
Lustrous (shiny surface)
Ductile (stretched into wire)
Malleable (hammered or bent into shape)
Metals are not…
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A: Ductile
B: Largest region of the periodic table
C: The most common type of element
D: Excellent insulators of
heat/electricity
Nonmetals
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Second largest region (toward
right) of periodic table
Poor conductors of heat and
electricity
Gases or brittle solids at room temp.
Any element that is neither a metal, a
metalloid, or a noble gas
Regions of the Periodic Table
Noble
Gases
Adapted from: http://web.buddyproject.org/web017/web017/images/periodic%20table.JPG 10/22/04
Metalloids
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Staircase region between metals and
nonmetals
Properties of both metals and nonmetals
Moderate electrical conductors at high
temperatures
E.g. boron, silicon, germanium, arsenic,
antimony, tellurium, astatine
Regions of the Periodic Table
Noble
Gases
Adapted from: http://web.buddyproject.org/web017/web017/images/periodic%20table.JPG 10/22/04
Noble Gases (Group 18)
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Far right column (group) of the periodic
table
Extremely unreactive
Very stable
Helium, Neon, Argon, etc.
Alkali Metals (Group 1)
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Soft, highly reactive metals
Good conductors of electricity
E.g. lithium, sodium, potassium, etc.
Alkaline-Earth Metals (Group 2)
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Harder, denser, stronger, but less
reactive than alkali metals
E.g. magnesium and calcium
Transition Elements
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Groups 3-12 or the d-block elements
In comparison to Groups 1&2:
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Metals, but not as reactive
Harder, denser, stronger, and have higher
melting points
E.g. iron, silver, gold, tin
Transition Elements, cont.
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Lanthanides and actinides
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Metals located at bottom of table (f-block)
Lanthanides (elements 58–71)
Actinides (elements 90-103)
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All have radioactive forms
E.g. Uranium
Halogens (Group 17)
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Most reactive of the non-metals
Combines easily with metals (particularly alkali
metals) to form salts
Latin: “salt-former”
Table salt
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Sodium chloride is made from chlorine in chemical
combination with the alkali metal sodium
E.g. fluorine, chlorine, bromine, iodine, etc.
Hydrogen
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Forms its own family
Behaves unlike no other element
Reacts rapidly with most other
elements such as oxygen
Combines with nitrogen to make
ammonia (used in fertilizers)
Other Families
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Nitrogen Family (Group 15)
Oxygen Family (Group 16)
Both families are nonmetals