Transcript The Periodic Table

The Periodic Table
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Elements are arranged in a way that
shows a repeating, or periodic, pattern.
Dmitri Mendeleev created the first periodic
table of the elements in 1869.
He ordered the ~70 known elements by
their atomic masses and their chemical
properties.
He found that some elements could not be
put into groups with similar properties and
at the same time stay in order.
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Modern Periodic Table
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Later, Henry Moseley carried on the
work.
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Moseley put the elements in order of
increasing atomic NUMBER.
He found that the position of the
element corresponded to its properties.
The modern periodic table shows the
position of the element is related to :
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Atomic number AND
Arrangement of electrons in its energy
levels
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Atomic Sizes using Periodic Table
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As we move down a group, atoms
become larger.
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Larger n = more shells = larger radius
As we move across a period, atoms
become smaller.
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More protons = more effective nuclear
charge, Zeff
More positive charge increases the
attraction of nucleus to the electrons in the
outermost shell, so the electrons are pulled
in more “tightly,” resulting in smaller radius
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Ionization energy
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Ionization energy of an ion or atom is the
minimum energy required to remove an
electron from the ground state of the isolated
gaseous atom or ion.
The first ionization energy, I1 is the energy
required to remove one electron from an atom.
Na(g)  Na+(g) + e
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Larger ionization energy, harder to remove
electron.
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Fig. 8.11
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Periodic Trends in Ionization Energy
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Highest = Fluorine
Ionization energy decreases down a
group.
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Easier to remove electrons that are
farther from the nucleus.
Ionization energy increases across a
period.
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Zeff increases, so it’s harder to remove
an electron.
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Electron Affinity
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Electron affinity is the energy change
when a gaseous atom gains an
electron to form a gaseous ion.
Gain 
Electron affinity: Cl(g) + e-  Cl-(g)
Lose 
Ionization energy: Cl(g)  Cl+(g) + e-
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Electronegativity
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Electronegativity is the ability of an atom
in a compound to ATTRACT an electron.
F has the highest electronegativity.
(She is “SO ATTRACTIVE!”)
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Metals
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Metallic character increases down a group and
from left to right across a period.
Metal properties:
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Lustrous (shiny)
Malleable (can be shaped)
Ductile (can be pulled into wire)
Conduct electricity
Metal oxides form basic ionic solids:
Metal oxide + water  metal hydroxide
 Metal oxides react with acids to form salt and
water
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General Trend Summary
Fr
Atomic Radius, Metallic Character
F
Electronegativity, Ionization Energy,
Electron Affinity
Atomic Radius,
Metallic Character
Electronegativity, Ionization Energy, Electron Affinity
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Ionization energy
Ionization energy of an ion or atom is the
minimum energy required to remove an
electron from the ground state of the isolated
gaseous atom or ion.
 The first ionization energy, I1 is the energy
required to remove one electron from an atom.
Na(g)  Na+(g) + e The 2nd ionization energy, I2, is the energy
required to remove an electron from an ion.
Na+(g)  Na2+(g) + e Larger ionization energy, harder to remove
electron.
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Periodic Trends in Ionization Energy
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Highest = Fluorine
Ionization energy decreases down a
group.
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Easier to remove electrons that are
farther from the nucleus.
Ionization energy increases across a
period.
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Zeff increases, so it’s harder to remove
an electron.
Exceptions: Removing the 1st and 4th p
electrons
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Electron Affinity
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Electron affinity is the energy change
when a gaseous atom gains an
electron to form a gaseous ion.
Electron affinity: Cl(g) + e-  Cl-(g)
Gain
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Ionization energy: Cl(g)  Cl+(g) + eLose
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Electronegativity
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Electronegativity is the ability of an atom
in a compound to ATTRACT electrons.
Fluorine has the highest
electronegativity.
Fluorine is “SO ATTRACTIVE!” (bats
eyelashes)
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Metals
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Metallic character increases down a group and
from left to right across a period.
Metals are found to the left of the zig-zag line
on the periodic table.
Metal properties:
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Lustrous (shiny)
Malleable (can be shaped)
Ductile (can be pulled into wire)
Conduct electricity
Metals form cations (positive ions)
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This means they lose 1-4 electrons
Therefore, they are usually found in IONIC
compounds
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Nonmetals
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Lower melting points than metals
Diatomic molecules are nonmetals.
The seven (7) diatomic molecules are:
Br2 I2
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N2
Cl2
H2
O2
F2
Two or more nonmetals form molecular
compounds with COVALENT bonds.
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Trends
See your book for full explanation.
Closer to F = more
ELECTRONEGATIVITY
 ELECTRON AFFINITY
 IONIZATION ENERGY
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Closer to Cs = more
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METALLIC CHARACTER
ATOMIC RADIUS
REACTIVITY
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