The Periodic Table
A. Dmitri Mendeleev
a. In 1869 arranged elements in order
of increasing atomic mass
b. He left vacant spaces in his table
where unknown elements could fit
Dmitri Mendeleev was so
.
confident in his table that
he used it to predict the
physical properties of three
elements that were yet
unknown-Sc, Ga and Gewhich were later discovered
between 1874 and 1885
B.
1.
2.
Geography of the Modern Table
7 periods (rows)-Row number indicates the
number of energy levels an atom has
Groups or Families (A Groups)-Column #
indicates # of valence (outside/bonding)
electrons ( those with 8 don’t bond-more
later)
elements with similar properties (also
called representative elements) are
placed in these groups and these groups
have names
Hydrogen





Hydrogen belongs to a
family of its own.
1 valance electron
Hydrogen is a
diatomic, reactive gas.
Hydrogen was involved
in the explosion of the
Hindenberg.
Hydrogen is promising
as an alternative fuel
source for automobiles
H
Alkali Metals-Group 1A



1 valence electron
Very reactive metals,
always combined with
something else in nature
(like in salt).
Soft enough to cut with
a butter knife
Alkali Metals
H
Alkaline Earth MetalsGroup 2A



2 valence electrons
Reactive metals that are
always combined with
nonmetals in nature.
Several of these
elements are important
mineral nutrients (such
as Mg and Ca
Alkaline Earth Metals
Alkali Metals
H
Transition Metals-B Groups

Elements in groups
3-12
– Valence electrons
vary



Less reactive
harder metals
Includes metals
used in jewelry and
construction.
Metals used “as
metal.”
Alkaline Earth Metals
Alkali Metals
H
Transition Metals
Boron Family-Group 3A



3 valence electrons
Elements in group
13
Aluminum metal
was once rare and
expensive, not a
“disposable metal.”
Alkaline Earth Metals
Alkali Metals
Transition Metals
Boron Family
H
Carbon Family-Group 4A


4 valence electrons
Contains elements
important to life and
computers.
– CARBON is found in
ALL living things
– Carbon is the basis for
an entire branch of
chemistry.

Silicon and Germanium
are important
semiconductors.
Alkaline Earth Metals
Alkali Metals
Transition Metals
Carbon Family
Boron Family
H
Nitrogen Family-Group 5A





5 valence electrons
Nitrogen makes up over ¾ of
the atmosphere.
Nitrogen and phosphorus are
both important in living
things.
Most of the world’s nitrogen
is not available to living
things so it is “fixed” by
special bacteria in the roots
of plants (peanuts too!).
The red stuff on the tip of
matches is phosphorus.
Alkaline Earth Metals
Alkali Metals
Transition Metals
Nitrogen Family
Carbon Family
Boron Family
H
Oxygen Family(Chalcogens)Group 6A



6 valence electrons
Oxygen is necessary
for respiration.
Many things that
stink, contain sulfur
(rotten eggs, garlic,
skunks,etc.)
Alkaline Earth Metals
Alkali Metals
Transition Metals
Oxygen Family
Nitrogen Family
Carbon Family
Boron Family
H
Halogens-Group 7A




7 Valence electrons
Very reactive,
volatile, diatomic,
nonmetals
Always found
combined with other
element in nature .
Used to make salts,
disinfectants and to
strengthen teeth.
Alkaline Earth Metals
Alkali Metals
Transition Metals
Halogens
Oxygen Family
Nitrogen Family
Carbon Family
Boron Family
H
The Noble Gases-Group 8A




8 valence electrons
so they have a full
outer energy shell.
VERY unreactive,
Used in lighted
“neon” signs
Used in blimps to
fix the Hindenberg
problem.
Transition Metals
Metals
Lanthanide Series
Actinide Series
Lanthanides and actinides are also called the “Rare Earth
elements. Actinides are radioactive.
Noble Gases
Halogens
Alkaline Earth Metals
Alkali Metals
H
3. Periodic Law-patterns within the table as
we move left to right and top to bottom
– Atomic Number (number of protons)
increases from left to right across a
period.
– Atomic mass (number of p+ and n)
increases from left to right across a
period.
– Density increase from top to bottom and
left to right as we add more atom particles
– Metals on the left-nonmetals on the right
Properties of Metals
 Metals are good
conductors of heat and
electricity
 Metals are malleable
(can be molded)
 Metals are ductile (can
be drawn into a wire)
 Metals have high tensile
strength
 Metals have luster
(shine)
Properties of Metalloids
Metalloids straddle the
border between metals
and nonmetals on the
periodic table.
 They have properties of both metals
and nonmetals.
NON-METALS
Opposite properties to metals
very brittle
exist in two of the three states of matter at room
temperature: most are gases [such as oxygen (diatomic-O2)
and a few solids (such as carbon).
Examples of Nonmetals
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
Microspheres
of phosphorus,
P, a reactive
nonmetal