The Periodic Table
Þ 1869 Russian
Chemist Dmitri Mendeleev grouped the
elements into the first orderly arrangement or Periodic Table.
Þ Elements are placed in order of increasingly atomic number.
Þ PERIODIC
LAW: When elements are placed in
order of increasing atomic number, there occurs a periodic repetition of
physical and chemical properties.
TO UNDERSTAND WHY THIS HAPPENS:
o
As the atomic
number changes in a neutral atom so does the sequence of electrons and it is
the electron configurations of the atom that determine it’s chemical and
physical properties!
o
Observed
properties of elements are the result of its electron
MAIN GROUP ELEMENTS
· Elements in groups 1, 2, and 13-18.
· They are also called the representative elements or the s and p blocks.
GROUPS all have the same number of valence electrons in their
outer shell
PERIODS tell you how many energy levels there are in an atom.
FOUR GROUPS
Within the main group have special names
Alkali
Metals Group 1
Alkaline
Earth Metals Group 2
Halogens Group 17
Noble
Gas Group 18
GROUP 1
Alkali Metals
· Highly reactive
· Reacts with water to form alkaline solutions
· 1 Valence Electron
· Usually stored in oil to prevent them from reacting
with moisture.
o
Alkali Solution:
They are basic in nature PH 8-14
· Never found as pure elements
· Soft and good conductors of electricity
o
Li Na, K, Rb, Cs,
Fr
o
Na [Ne] 3s1
o
K [Ar] 4s
GROUP II
Alkali Earth Metals
· 2 Valence Electrons
· Highly Reactive but less than Alkali Metals
· Silvery colored, soft, low density metals
o
Mg [Ne] 3s2
o
Ca [Ar] 4s2
GROUP 17
Halogens
· Most reactive of the non-metals
· 7 Valence electrons
· When they react they often gain one electrons
o
F, Cl, Br, I, At
o
F [He] 2s22p5
o
Cl [Ne] 3s23p5
GROUP 18
Noble Gas
· All are non metals and gases at room temperature
· Extremely limited ability to react chemically
· Have a full set of electrons in the outer most shell
· Possess a stable electron configuration
Elements are
divided into 3 classifications
o
Blue METALS
o
Green: METALLOIDS
o
Yellow:
NON-METALS
ALL ELEMENTS ON THE LEFT SIDE AND IN THE MIDDLE OF THE
TABLE (except for Hydrogen) are metallic elements or METALS. Hydrogen….
Although to the left of the line is a non-Metal… it is NOT in Group 1… It is not
a non-metal. It is in a group by its self.
Characteristics of METALS:
· Excellent conductor of electricity
· Excellent conductors of heat
· Ductile and malleable
o
Ductile: Metal
into wire
o
Malleable: Means
you can shape it (Iron, Copper)
DISTINGUISHING PROPERTY: (THIS WILL BE ON THE TEST)
·
Metals generally have fewer electrons in the outer
level (valence Shells) than non-metals
and they generally loose electrons when they undergo reactions.
METALLOIDS:
Ø All the elements that touch
the diagonal line
Ø Found in the middle periodic
table
Ø Have properties of metals
and non-metals
METALS
Ø Are separated from the
nonmetallic elements by a diagonal step like line.
Ø Are Shiny
Ø Conduct Electricity
Ø Conduct Heat
Ø They have a fewer amount of
valence electrons
NON-METALS
Ø Lie on the right of the
periodic table
Ø Not colorful
Ø Not Shiny
Ø Poor Conductors of electricity
Ø When they react they Gain
electrons
TRANSITION
METALS
Ø Everything in the middle on
the periodic table and at the bottom Group 3-1
Ø Have two Groups
o MAIN TRANSITION ELEMENTS
§ Located in main body of
table
o INNER TRANSITION ELEMENTS
§ 2 long rows of 14 elements
placed just below the table.
§ Sometimes called the f block
LANTHANIDES
Ø Elements Z (atomic number)=
58-71
Ø All have predicted structure
with 2 electrons in the outer level
Ø 4f sublevel bing filled
ACTINIDE
SERIES
Ø Elements Z 89 through 102
Ø Highly unstable
Ø They are radioactive
The Best Known ACTINIDES:
o Uranium Z=92
o Plutonium Z= 94 are the best
known
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