1. Periodic Table
Arranging Elements

2. The Pattern -1860's: Russian chemist, Dmitri Mendeleev studies
elements
-discovers that elements are periodic , they follow a
regular, repeating pattern based on increasing
atomic mass
-recognizes similar physical and chemical
properties in every 8th element
-his arrangement called a
"Periodic Table"
-also recognized that elements
were missing from his table
-used pattern to predict existence
and properties of missing
-those missing elements have now
been discovered

3. Changing the Arrangement
-some elements didn't fit Mendeleev's pattern
-1914: Henry Moseley rearranged periodic table by atomic
number (the # of protons in one atom of an element)
instead of atomic mass
-all elements fit new arrangement
-all new elements discovered since also
followed this periodic law (the physical and chemical
properties of elements are periodic functions of their
atomic number)
Henry Moseley

5. Navigating the Table
-periodic table contains information that can help
you understand it
-elements classified as metals, nonmetals, or
metalloids
-also classified by number of electrons in
outer energy level (valence electrons)
-zig-zag line identifies metals, nonmetals, and
metalloids:
Metals - found to left of zig-zag & have few
electrons in outer level
Nonmetals - found to right of zig-zag &
most have a nearly complete set of electrons in
outer level
Metalloids – border zig-zag line and
outer levels are about half complete

6. Atomic Number Symbol Element Name Atomic Mass
-each square contains information about a different
element including:
Atomic Number
Symbol
Element Name
Atomic Mass

7. -names and symbols of each element approved
by panel of scientists
-some elements named for important scientists:
mendelevium or einsteinium
-others named for geographical regions:
germanium or californium
-symbols are usually one or two letters (if 1 letter -
always capitalized, if 2 letters - 1st capitalized, 2nd
lowercase)
-5 basic patterns for writing chemical symbols

8. Patterns for Chemical Symbols
Example
1st letter of name
S - sulfur
1st 2 letters of name
Ca - calcium
1st letter & 3rd or
later letter
Mg - magnesium
letter(s) of word other
than English name
Pb - lead (from latin
plumbum )
1st letter of root words
that stand for the atomic
number (used for elements
whose official names
have not yet been
chosen)
Uut - ununtrium (for
atomic # 113)

9. Period Group -rows of periodic table called periods
-properties in each row follow a repeating
pattern
-physical and chemical properties change gradually
(from left to right) as elements change from metals
to nonmetals
-columns (top to bottom) called groups
-elements in each group have similar properties
-groups also called families
Period
Group