Transcript Arrangement of the Periodic Table

The History and
Arrangement of the
Periodic Table
History of the Periodic Table
► 1869
– Dmitri Mendeleev (Russian Chemist)
thought elements may have something in
common.
► Organized the elements into a table
► Made each element a card and listed its
properties known at the time (mass,
density, color, melting point and valence
number).
Dmitri Mendeleev (cont.)
► Mendeleev
organized each card (element)
according to its atomic mass (mass #)
► Noticed a repeating pattern of valence
numbers (1,2,3,4,5 etc..)
► Noticed elements fell in to columns (groups)
► Noticed all elements in a column had the
same valence number and showed similar
physical and chemical properties.
Henry Moseley
► Mendeleev
left blank spaces in his table so
elements would line up – he also predicted
what properties the undiscovered elements
would have.
► 1913 – Henry Moseley (English Scientist)
changed the arrangement of the periodic
table. Instead of by increasing atomic mass
(mass #), it was arranged by increasing:
atomic number (# of protons).
Arrangement of the Periodic
Table
► Systematic
arrangement of the elements
► Arranged by atomic number and properties
► Numbered groups / families are in vertical
columns
► Periods are by amount of energy levels in
horizontal rows (1-7)
► Divided into metals, nonmetals and
metalloids
Metals - properties
► Elements
that begin at the left side of the
periodic table
► Good conductors of electricity
► Shiny
► Ductile – can be drawn into thin wires
► Malleable – can be hammered into thin
sheets and other shapes
► High melting point
► Tend to loose electrons
Nonmetals - properties
► Elements
that are to the right of the zigzag
on the periodic table
► Not shiny, dull in appearance
► Do not conduct heat or electricity
► Are brittle and break easily
► Cannot be drawn into wire or hammered
into sheets
► Lower densities
► Lower melting points
► Tend to gain electrons
Metalloids - properties
► Elements
that are found along both
sides of the zigzag line
► Solids
► Can be shiny or dull conduct heat and
electricity better than nonmetals but
not as well as metals
► Both ductile and malleable
Chemical Groups (Families)
► Elements
that are in the same group or
family (column) of the Periodic Table
have similar properties because they
have the same number of valence
electrons
Group (Family) 1 - Alkali Metals
►1
valence electron in outer energy
level
► Very reactive substances so it easily
bonds with other substances
► Easily loses 1 electron to form a stable
+1 ion (ionic bond)
► Never found alone in nature
► Soft, silver-white, shiny
Group (Family) 2 - Alkaline Earth
Metals
►2
valence electrons in outer energy level
► Loses 2 electrons to form +2 ions
► Second most reactive elements but not as
reactive as group #1, so bonds easily with
other substances
► Never found alone in nature
► Will always bond ionically in nature
► Found combined with oxygen and other
non-metals in the Earth’ crust
Groups 3-12
►1
The Transition
Metals
or 2 valence electrons
► Can lose and or share valence
electrons
► Can have many multiple electrons in
2nd to last energy levels
► Common metals – gold, silver & copper
► The U.S. imports at least 60 of these
types of elements which are strategic
and vital for our economy
From Metals to Nonmetals
(outer energy level)
►
Group 13 – Boron Group/Family
3 valence electrons
- metalloids and metals in group
- usually bonds covalently
►
Group 14
Carbon Group
4 valence electrons
- non-metals, metals and metalloids
- will always bond covalently ( electron sharing)
- contain elements which are essential for cell functions
►
Group 15
Nitrogen Group
5 valence electrons
- non-metals, metalloids and metals
- will always bond covalently
► Group 16
Oxygen Group
6 valence electrons
- non-metals, metalloids and metals
- will bond covalently and ionically in nature
►
Group 17
Halogen Group
7 valence electrons
- all non-metals that are very reactive and form compounds
called halides ( salts)
- bonds covalently and ionically
►
Group 18
Noble Gases
8 valence electrons
- colorless
- non-reactive ( inert ) / very stable
- have a full outer shell filled
with electrons
- non-metals
Rare Earth Elements
(Inner Transition Metals)
► First
Row – Lanthanide Series
- naturally found rare Earth metals
- all but one is non-radioactive
► Second
Row – Actinide Series
- most are man-made and radioactive
- many are short-lived