Periodic Table

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Periodic Table

• History Classification

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Mendeleevs Periodic Table-1869
Dmitri Mendeleev

• Organized by increasing atomic mass
• Elements with similar properties are grouped
  together
• Predicted properties of undiscovered elements

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A Spiral Periodic Table
Stowe Periodic Table
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Mayan Periodic Table
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Henry Mosely (1913, British)

• Organized elements according to atomic number
• Resolved discrepancies in Mendeleevs arrangements

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Period
The Periodic Table
Group or Family
Roman Numeral Valence electrons
Group or family
Period
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Periods and Groups

• Horizontal Rows
• Periods
• Numbered 1-7
• Groups or Families
• groups contain elements with similar properties
  in vertical columns.
• Group Numbers
• use the letter A for the representative elements
  (1A to 8A) and the letter B for the transition
  elements.
• also use numbers 1-18 to the columns from left to
  right

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Periods and Groups
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Names of Some Representative Elements
Several groups of representative elements are
known by common names.
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The Properties of a Group the Alkali Metals

•   Easily lose valence electron
• (Reducing agents)
•   React violently with water
•   Large hydration energy
•   React with halogens to form
• salts

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Properties of Metals

• Metals are good conductors of heat and
  electricity
• Metals are malleable
• Metals are ductile
• Metals have high tensile strength
• Metals have luster

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Examples of Metals
Potassium, K reacts with water and must be stored
in kerosene
Copper, Cu, is a relatively soft metal, and a
very good electrical conductor.
Zinc, Zn, is more stable than potassium
Mercury, Hg, is the only metal that exists as a
liquid at room temperature
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Properties of Nonmetals
Carbon, the graphite in pencil lead is a great
example of a nonmetallic element.

• Nonmetals are poor conductors of heat and
• electricity
• Nonmetals tend to be brittle
• Many nonmetals are gases at room temperature

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Halogens
Group 7A(17) the halogens, includes chlorine,
bromine, and iodine.
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Examples of Nonmetals
Microspheres of phosphorus, P, a reactive
nonmetal
Sulfur, S, was once known as brimstone
Graphite is not the only pure form of carbon, C.
Diamond is also carbon the color comes from
impurities caught within the crystal structure
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Properties of Metalloids
Metalloids straddle the border between metals and
nonmetals on the periodic table.

• They have properties of both metals and
  nonmetals.
• Metalloids are more brittle than metals, less
  brittle than most nonmetallic solids
• Metalloids are semiconductors of electricity
• Some metalloids possess metallic luster

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Silicon, Si A Metalloid

• Silicon has metallic luster
• Silicon is brittle like a nonmetal
• Silicon is a semiconductor of electricity

Other metalloids include

• Boron, B
• Germanium, Ge
• Arsenic, As
• Antimony, Sb
• Tellurium, Te