Chemistry Chapter 5

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Chemistry Chapter 5

• The Periodic Law

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Mendeleevs Periodic Table
Dmitri Mendeleev
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Modern Russian Table
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Chinese Periodic Table
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Stowe Periodic Table
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A Spiral Periodic Table
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Triangular Periodic Table
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Mayan Periodic Table
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Giguere Periodic Table
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Orbital filling table
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Periodic Table with Group Names
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The Properties of a Group the Alkali Metals

• Easily lose valence electron
• (Reducing agents)
• React violently with water
• Large hydration energy
• React with halogens to form salts

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Properties of Metals

• Metals are good conductors of heat and
  electricity
• Metals are malleable
• Metals are ductile
• Metals have high tensile strength
• Metals have luster

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Examples of Metals
Potassium, K reacts with water and must be stored
in kerosene
Copper, Cu, is a relatively soft metal, and a
very good electrical conductor.
Zinc, Zn, is more stable than potassium
Mercury, Hg, is the only metal that exists as a
liquid at room temperature
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Properties of Nonmetals
Carbon, the graphite in pencil lead is a great
example of a nonmetallic element.

• Nonmetals are poor conductors of heat and
• electricity
• Nonmetals tend to be brittle
• Many nonmetals are gases at room temperature

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Examples of Nonmetals
Microspheres of phosphorus, P, a reactive
nonmetal
Sulfur, S, was once known as brimstone
Graphite is not the only pure form of carbon, C.
Diamond is also carbon the color comes from
impurities caught within the crystal structure
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Properties of Metalloids
Metalloids straddle the border between metals and
nonmetals on the periodic table.

• They have properties of both metals and
  nonmetals.
• Metalloids are more brittle than metals, less
  brittle than most nonmetallic solids
• Metalloids are semiconductors of electricity
• Some metalloids possess metallic luster

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Silicon, Si A Metalloid

• Silicon has metallic luster
• Silicon is brittle like a nonmetal
• Silicon is a semiconductor of electricity

Other metalloids include

• Boron, B
• Germanium, Ge
• Arsenic, As
• Antimony, Sb
• Tellurium, Te

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Determination of Atomic Radius
Half of the distance between nucli in covalently
bonded diatomic molecule
"covalent atomic radii"
Periodic Trends in Atomic Radius

• Radius decreases across a period

Increased effective nuclear charge due to
decreased shielding

• Radius increases down a group

Addition of principal quantum levels
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Table of Atomic Radii
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Ionization Energy - the energy required to
remove an electron from an atom

• Increases for successive electrons taken from
• the same atom

• Tends to increase across a period

Electrons in the same quantum level do not
shield as effectively as electrons in inner
levels
    Irregularities at half filled and filled
sublevels due to extra repulsion of
electrons paired in orbitals, making them
easier to remove

• Tends to decrease down a group

Outer electrons are farther from the nucleus
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Ionization of Magnesium
Mg 738 kJ ? Mg e-
Mg 1451 kJ ? Mg2 e-
Mg2 7733 kJ ? Mg3 e-
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Table of 1st Ionization Energies
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Another Way to Look at Ionization Energy
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Electron Affinity - the energy change associated
with the addition of an
electron

• Affinity tends to increase across a period

• Affinity tends to decrease as you go down
• in a period

Electrons farther from the nucleus experience
less nuclear attraction
Some irregularities due to repulsive forces in
the relatively small p orbitals
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Electronegativity
A measure of the ability of an atom in a
chemical compound to attract electrons

• Electronegativities tend to increase across
• a period

• Electronegativities tend to decrease down a
• group or remain the same

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Table of Electron Affinities
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Ionic Radii
Cations

• Positively charged ions

• Smaller than the corresponding
• atom

Anions

• Negatively charged ions

• Larger than the corresponding
• atom

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Summation of Periodic Trends
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Table of Ion Sizes
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Periodic Table of Electronegativities