The Periodic Table
most of the pure elements are solid at room temperature, only 11
naturally occurring elements are a gas, and only 2 elements are liquid at
room temperature
Dmitri Mendeleev (1829-1869)
• organized a “Periodic Table”
(only knew about 63 elements at
the time) based on increasing
atomic mass
– the properties of elements
had something to do with
their mass
• even left empty spaces to be
filled in later!!!
3 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
– located to the right of the zig-zag line in the
periodic 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 and
nonmetals
• Groups are the vertical columns.
– elements have similar, but not identical,
properties
• most important property is that they have
the same # of valence electrons
Alkali Metals
• soft metals
• most reactive of the metals because they all lose
one valence electron VERY easily
http://www.microchem.de/elec000a-k.JPG
Alkaline Earth Metals
• harder and denser than alkali metals
• not as reactive as the alkali metals because
have two (out of 8) valence electrons
Transition Metals (Elements)
• display typical metallic characteristics
• give away valence electrons depending 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 valence
level is full (2,8,8….)
– do not lose any valence electrons
• colorless, odorless gases
Tendency to gain valence electrons
Mixed Groups
• not as similar to each other as other groups
• usually named after the first element in the
group (B C N O)
Rare Earth Elements
• not actually rare
• some are synthetically produced
• used in the nuclear industries, metallurgy,
ceramics, electrical components…
• Periods are the horizontal rows
– may not have similar properties
– however, there is a mathematical pattern to
their properties as you move across the table
1
2
3
4
5
6
7
6
7
radius increases
radius
increases