Download The History of the Modern Periodic Table

The History of
the Modern
Periodic Table
History of the
Periodic Table
• Dmitri Mendeleev –
first to organize
elements according to
their properties
• Mendeleev ordered
the elements
according to
increasing atomic
mass
Henry Mosely
• British Scientist 1911
• Re-ordered the periodic table in
order of Proincreasing atomic
number instead of mass.
• blems with the Mendeleev table
disappeared.
History of the
Periodic Table
• Periodic Law: The physical
& chemical properties of the
elements are periodic
functions of their atomic
numbers.
History of the
Periodic Table
• Periodic Table: arrangement of
elements in order of their
atomic numbers so that
elements with similar properties
fall in the same column.
Periodic Table
Geography
The horizontal rows of the periodic table
are called PERIODS.
The elements in any group
of the periodic table have
similar physical and chemical
properties!
The vertical columns of the periodic table
are called GROUPS, or FAMILIES.
Alkali Metals (yellow)
Alkali Metals
• 1st column on the
periodic table (Group 1)
not including hydrogen.
• Very reactive metals,
always combined with
something else in nature
(like in salt).
• Soft enough to cut with
a butter knife
Alkaline Earth Metals
(Blue)
Alkaline Earth Metals
• Second column on the
periodic table. (Group 2)
• Reactive metals that are
always combined with
nonmetals in nature.
• Several of these elements
are important mineral
nutrients (such as Mg and
Ca
Transition Metals
(orange!)
Transition Metals
• Elements in groups 3-12
• Less reactive harder
metals
• Includes metals used in
jewelry and
construction.
• Metals used “as metal.”
Halogens (green)
Halogens
• Elements in group 17
• Very reactive, volatile,
diatomic, nonmetals
• Always found combined
with other elements in
nature .
• Used as disinfectants
and to strengthen teeth.
Noble Gases (Red)
The Noble Gases
• Elements in group 18
• VERY unreactive,
monatomic gases
• Do not combine with
other elements
• Used in lighted “neon”
signs
• Have a full valence
shell.
The Odd Ones
Hydrogen
• Hydrogen belongs to
a family of its own.
• Hydrogen is a
diatomic, reactive
gas.
• Hydrogen is
promising as an
alternative fuel
source for
automobiles
Boron Family
• Elements in group 13
• Aluminum metal was
once rare and
expensive, not a
“disposable metal.”
Carbon Family
• Elements in group 14
• Contains elements
important to life and
computers.
• Carbon is the basis for an
entire branch of
chemistry.
• Silicon and Germanium
are important
semiconductors.
Nitrogen Family
• Elements in group 15
• 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.
• The red stuff on the tip of
matches is phosphorus.
Metalloids
• Along the stair step line of the periodic
table
• Boron, Silicon, Germanium, Arsenic,
Antimony, Tellurium
• Have characteristics of both metals and
nonmetals
The periodic table is the most important
tool in the chemist’s toolbox!
Metals, Nonmetals, and Metalloids
Metallic character increases down and to
the left on the table and nonmetallic character
increases up and to the right on the table.
Atomic Radii Increase
Atomic Radii Increase
Valence Electrons
• electrons available to be lost,
gained, or shared in the
formation of chemical
compounds
• usually in the outermost s and p
orbitals for main group
elements (Families 1 & 2, and
Families 13-18)
Valence Electrons for each group
•
•
•
•
•
•
•
•
Group 1: valency +1
Group 2: +2
Group 3: +3
Group 4: 4
Group 5: -3
Group 6: -2
Group 7: -1
Group 8: 0 stable. does not like to react with others.
• With each electron shell wanting to gain up to 8 electrons on outer
shell
• An electron configuration shows the
number of electrons in each orbital in a
particular atom.
• Keep this in mind about the number of
valence electrons and the Roman numeral
column number: The IA family has 1
valence electron; the IIA family has 2
valence electrons; the VIIA family has 7
valence electrons; and the VIIIA family has
8 valence electrons. So for the families
labeled with a Roman numeral and an A,
the Roman numeral gives the number of
valence electrons.
Neutral Atoms vs. Ions
• Cations – form positive ions by losing
electrons (metals)
• Anions – form negative ions by gaining
electrons (nonmetals)
Ionization Energy
• Energy required to remove one
electron from a neutral atom of an
element.
• Increases left to right across the
periodic table.
• Increases going from the bottom to
the top of a group.
• For each successive electron in an
atom that is removed, the ionization
energy increases.
Ionization Energies Increase
Electron Affinity
• energy change that occurs when a neutral atom gains an
electron
• Most atoms release energy when they acquire electrons.
Electronegativity
• measure of an atom’s ability to attract electrons
in a chemical compound
• If electron affinity is high, electronegativity will be
high.
Alkaline Metals
Periodic Table
Alkaline Earth Metals
Noble Gases
Halogens
Metalloids
Transition Metals
Lanthanides
Actinides
Group 13 boron
family
Group 14 carbon
family
Group 15
pnictogens
Group 16
chalcogens
Metals, Nonmetals, and Metalloids
Metallic character increases down and to the
left on the table and nonmetallic character
increases up and to the right on the table.
Periodic Table w/ orbitals
Interactive Periodic Table
• http://center.acs.org/periodic/tools/PT.ht
ml