Electron Configuration and the Periodic Table

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Electron Configuration and the Periodic Table

• Chemistry Chapter 5 Section 2

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Periods
http//www.bpc.edu/mathscience/chemistry/history_o
f_the_periodic_table.html

• Periods on the periodic table
• Show a horizontal trend in changing properties
• Show the level of outer shell electrons and
  orbitals filling

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Blocks

• The periodic table can be broken into blocks

http//www.meta-synthesis.com/webbook/35_pt/pt_dat
abase.php?Button1950-1999Formulations
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S block

• Groups 1 and 2
• Highest energy electron is in an s orbital
• Powerful reducing agents
• Group 1 Alkali metals
• Soft, silvery, low melting points, not found
  uncombined in nature
• Group 2 Alkaline Earth metals
• Harder, denser, higher MP than Group 1, not found
  uncombined in nature

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Sample Problem 5-1

• Without looking at the periodic table, give the
  group, period and block for Xe6s2
• Without looking at the periodic table, write the
  electron configuration of the group 1 element in
  the third period. Is this element likely to be
  more or less reactive than the previous element?

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D block

• Transition elements
• Fill d block, which is one level lower than the
  valence shell
• Electron configuration may vary depending on
  half-full and totally full d orbital stablity
• Properties
• Metallic luster, good conductors, may be
  unreactive

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Sample problem 5-2

• An element has the electron configuration
  Kr4d55s1. Without looking at the periodic
  table, identify the period, block and group in
  which this element is located. Then consult the
  periodic table to identify the element.

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P block

• Groups 13-18
• Sometimes called main-group elements
• Properties vary from metallic on left to
  metalloid to nonmetallic to noble gas on right
• Groups within this block
• Halogens most reactive nonmetals
• Noble gases nonreactive

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Sample Problem 5-3

• Without looking at the periodic table, write the
  outer electron configuration for the group 14
  element in the second period. Then name the
  element and label it as metal, metalloid or
  nonmetal.

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F block

• Two rows below the periodic table
• F orbital 2 levels lower than valence filling
• Follow Lanthanum and Actinium
• Lanthanide REE
• Actinide all radioactive

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Sample problem 5-4

• The electron configurations of four elements are
  written at the top of page 139. For each
  element, name the block and group in the periodic
  table in which it is located. Then name the
  element using the periodic table. Identify each
  element as a metal, metalloid or nonmetal.
  Finally, describe it as likely to be of high or
  low reactivity.