The Periodic Table
most of the pure elements are solid at room temperature, only 11naturally occurring elements are a gas, and only 2 elements are liquid atroom temperature
Dmitri Mendeleev (1829-1869)
•organized a “Periodic Table”(only knew about 63 elements atthe time) based on increasingatomic mass
–the properties of elementshad something to do withtheir mass
•even left empty spaces to befilled in later
Main “categories” of elements
•Metals
–shiny
–ductile
–malleable
–good conductors of heat and electricity
–have high melting points
–will corrode (rust) in water or air
–generally give away electrons
•Nonmetals or gases
–located to the right of the zig-zag line in theperiodic table
–often are different from one another
–dull
–do not conduct heat and electricity
–are not malleable nor ductile
–have a tendency to gain electrons
•Metalloids
–elements on the “zig-zag line”
–have some characteristics of both metals andnonmetals
•Groups are the vertical columns.
–elements have similar, but not identical,properties
•most important property is that they havethe same # of valence electrons
Alkali Metals
•most reactive of the metals because they all loseone valence electron VERY easily
•soft metals
http://www.microchem.de/elec000a-k.JPG
Alkaline Earth Metals
•harder and denser than alkali metals
•not as reactive as the alkali metals
Transition Metals (Elements)
•display typical metallic characteristics
•can share or give away valence electronsdepending what they chemically combine with
Halogens
•form diatomic molecules
–(F2 Br2 I2 Cl2 )
•all gain one valence electron VERY easily
Noble Gases
•mostly unreactive because their valencelevel is full (2,8,8….)
•colorless, odorless gases
Mixed Groups
•not as similar to each other as other groups
•usually named after the first element in thegroup (B C N O)
Rare Earth Elements
•many are synthetically produced (not actually rare)
•have been separated from the others to make thetable not as wide
•used in the nuclear industries, metallurgy,ceramics, electrical components…
•Periods are the horizontal rows
–do NOT have similar properties
–however, there is a pattern to theirproperties as you move across the table
