Download The Periodic Table

The Periodic Table
Ms. Pollock
Physical Science
2008-2009
Organizing the Elements
• Dmitri Mendeleev’s periodic table published in
1869 in Russia
• Born in Siberia in 1834
• Chemistry professor at University of St.
Petersburg
• Wrote textbook for students; led to
development of periodic table
• Extremely accurate periodic table for time
Dmitri Ivanovich Mendeleev
• http://www.aip.org/hist
ory/curie/periodic.htm
Mendeleev’s Table
• Just over 60 elements identified at the time
• Organized by atomic weights (masses) and
found that the properties of elements repeated
periodically
• Not all elements known, so some spaces left
blank
• Accurately predicted properties of elements not
yet discovered
Mendeleev’s Table
Improving the Periodic Table
• Henry Moseley, 1913
• Found that some elements did not line up
perfectly in Mendeleev’s table
• Re-ordered elements by atomic number, rather
than atomic mass
• British; studied with Ernest Rutherford
• Killed in World War I
Henry Moseley
• http://www.chemistry.co
.nz/henry_moseley.htm
The Atom and the Periodic Table
• Elements sorted according to properties
• Groups – vertical columns; similar properties
– Same group = electrons in same energy level
– Electrons in same energy level = similar chemical
properties and behavior
• Periods – horizontal rows
– Each row a new energy level
– Row 1 = 1 energy level
– Row 7 = 7 energy levels
The Atom and the Periodic Table
Electron Dot Diagrams
• Elements in same group have the same number
of electrons in their outer energy levels.
• The outer energy level can be drawn using an
electron dot diagram.
• The symbol of the element and a series of dots
are used to represent electrons in the outer
energy levels.
• Developed by American chemist G. N. Lewis
Electron Dot Diagrams
• http://www.ausetute.com.au/lewisstr.html
• Write the symbol first.
• Then, place one electron at each side of the
symbol.
• Finally, pair electrons until all valence (outer
shell) electrons are accounted for.
Electron Dot Diagrams
Cl
Group 17: Valence electrons cannot exceed
8 (octet rule), so take the group number
(17) and subtract 10.
17 – 10 = 7 valence electrons
Electron Dot Diagrams
Cl
Electron Dot Diagrams
Cl
Electron Dot Diagrams
Cl
Electron Dot Diagrams
Cl
Electron Dot Diagrams
Cl
Electron Dot Diagrams
Cl
Electron Dot Diagrams
Cl
Regions on the Periodic Table
• Several areas on periodic table with specific
names
• Left = metals (mostly solids)
• Right = nonmetals (mostly gases)
• Zig-zag line = metalloids
• Extra rows = Lanthanides and Actinides
Periodic Table Regions (Metals)
http://www.dkimages.com/discover/previews/796/939317.JPG
Periodic Table Regions (Nonmetals)
Periodic Table Regions (Metalloids)
katie-maggie-mettaloids-g.wikispaces.com
Elements in the Universe
• Modern technology making elements in other
parts of universe easy to identify
• Hydrogen and helium thought building blocks
of other elements
• Many elements found only in stars or as a result
of the decay of other elements
http://images.iop.org/objects/physicsweb/world/16/7/3/pwpia1_07-03.jpg