Transcript The Periodic Table

The Periodic Table
History, Organization and
Trends
Lavoisier, Dobereiner, & Newlands
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1790- Lavoisier, 23 elements
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1870- Dobereiner, triads, 70 elements
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1864- John Newlands, Law of Octaves
Dimitri Mendeleev (1834-1907)
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A Russian chemist who in 1869
published an organized scheme
for the elements called the
Periodic Table. The elements
were arranged in ascending order
of atomic mass and also by
properties. He was able to
predict the properties of
undiscovered elements because
of their placement in the periodic
table. (gallium, scandium, germanium)
1875
1886
Henry Mosely (1887-1915)
Henry Moseley
rearranged the
elements in 1913
by ascending
order of atomic
number.
The Modern Periodic Table
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Periodicity- the tendency to recur at
regular intervals
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Periodic Law: The properties of the
elements repeat periodically when the
elements are arranged in increasing
order by their atomic numbers.
Modern PT Organization
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Groups/ families -vertical columns
(similar properites)
Periods- horizontal rows
Representative elements- Group “A”
Transition elements- Group “B”
Metals- LEFT
Nonmetals- RIGHT
Metalloids- On LINE
Groups of elements
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Metals
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Alkali
Alkaline Earth
Transition
Inner transition
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Nonmetals
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Halogens
Noble gases
Hydrogen is a nonmetal
Properties of Metals
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Solid
High melting point
Shiny, luster
Good conductors of heat and electricity
Malleable
Ductile
Few valence electrons
Reacts by giving up electrons
Main group metals are highly predictable,
transition metals are not.
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Alkali metals - group 1, 1 valence electron, highly
reactive so not found free in nature, reacts with
water to give off hydrogen gas, very soft
Alkali earth metals – group 2, 2 valence electrons,
reactive and not found free in nature, reacts some
with water, fairly hard
Transition metals – valence electrons vary, some
are unreactive to water, some are found free in
nature
Lanthanide series – also called the rare earth
elements, part of the inner transition elements,
unpredictable, natural abundance on Earth is less
than 0.01%
Actinide series – part of the inner transition
elements, all are radioactive, unpredictable
Properties of Nonmetals
Brittle if solid, many are gases
Dull
Poor conductor of heat, does not conduct
electricity
Seven diatomic gases-H2, N2, O2, F2, Cl2, Br2, I2
3-8 valence electrons
Reacts by taking electrons from other atoms
More reactive nonmetals are at top of group
Halogens- group 17, 7 valence electrons, reacts
by taking electrons from other atoms
Noble gases- group 18, 8 valence electrons, inert
gases, monatomic gases, most do not react with
other elements
* Hydrogen is considered a nonmetal
Metalloids
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Has properties of metals and
nonmetals
Semiconductors
Valence Electrons
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Group “A” number tells valence
electrons
6.3 Trends
Atomic Radius
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How Big is the atom?
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Group Trend – decreases left to right
Period trend- increases top to bottom
Ionic Radius
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How big is the ion?
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Group trend- Increases top to bottom
(note metalloid line)
Period trend – decreases to metalloid
line, jumps up, then decreases again
Ion- an atom or a bonded group of atoms
that has a positive or negative charge
Ionization Energy
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How hard is it to remove 1 electron?
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Group Trend- decreases top to bottom
Period Trend- increases left to right
Octet rule- atoms gain, lose or share
electrons to acquire a full set of valence
electrons
Electronegativity
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How hard does the atom pull on
shared electrons?
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Group Trend- Decreases top to bottom
Period Trend- Increases left to right