WEdnesday 3/23/11

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WEdnesday3/23/11
CHEMISTRY

• Bell Ringer

• Assignment

1. Bell Ringer
2. Periodic Table Notes

• Pick up the notes off the front demo table, turn
  in the Periodic Table Activity from the last two
  days the extra credit
• Try to answer this question on the back
• If you were an alchemist (first type of chemist)
  and were given a set of substances like the one
  up front, how would you classify and characterize
  these? What experiments could you do to
  determine properties?
• .

I can. Identify the electron configuration of an
element and the characteristics of that element
HOMEWORK Review your notes
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Alchemy !!
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Reading the Periodic Table
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A. Mendeleev

• Dmitri Mendeleev (1869, Russian)
• Organized elements by increasing atomic mass.
• Elements with similar properties were grouped
  together.
• There were some discrepancies.

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Mendeleevs Periodic Table
Dmitri Mendeleev
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Modern Russian Table
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A Spiral Periodic Table
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Mayan Periodic Table
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B. Moseley

• Henry Moseley (1913, British)
• Organized elements by increasing atomic number.
• Resolved discrepancies in Mendeleevs arrangement.

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The Periodic Table
Period
Group or Family
Group or family
Period
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Rows

• The horizontal rows of the periodic table are
  called periods.
• Elements in a period are not alike in properties.
  
• The first element in a period is usually an
  active solid, and the last element in a period is
  always an inactive gas.

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Rows

• Atomic size (number of protons) increases from
  left to right across a period.
• Atomic mass (number of protons neutrons)
  increases from left to right across a period.
• Metals on left, nonmetals on right

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Columns

• The vertical (up and down) columns of the
  periodic table (there are 18) are called groups
  or families.
• Elements in the same group or family have similar
  characteristics or properties.

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Metallic Character

• Metals
• Nonmetals
• Metalloids

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Properties of Metals

• Metals are good conductors of heat and
  electricity
• Metals are malleable (flattened molded)
• Metals are ductile (can be rolled pulled into
  wire)
• Almost all metals have luster (shine)

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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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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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Blocks

• Main Group Elements
• Transition Metals
• Inner Transition Metals

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ALKALI METALS

• very reactive metals that do not occur freely in
  nature
• malleable, ductile, good conductors of heat and
  electricity.
• softer than most other metals, can be cut with
  knife
• React violently with water (explode)
• React with halogens to create salts

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ALKLINE EARTH METALS

• Very reactive metals
• not found free in nature
• harder, denser, and stronger than alkali metals
• Have higher melting points than group 1, and
  are less reactive

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TRANSITION METALS

• ductile and malleable, and conduct electricity
  and heat
• iron, cobalt, and nickel, are the only elements
  known to produce a magnetic field.

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RARE EARTH ELEMENTS

• many are man-made

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OTHER METALS

• are ductile and malleable
• solid, have a relatively high density, and are
  opaque

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METALLOIDS

• have properties of both metals and non-metals
• some of the metalloids, such as silicon and
  germanium, are semi-conductors. This property
  makes metalloids useful in computers and
  calculators

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NON-METALS

• not able to conduct electricity or heat very well
• very brittle, and cannot be rolled into wires or
  pounded into sheets
• exist in two of the three states of matter at
  room temperature gases (such as oxygen) and
  solids (such as carbon).
• have no metallic luster, and do not reflect
  light.

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HALOGENS

• "halogen" means "salt-former" and compounds
  containing halogens are called "salts"
• exist in all three states of matter
• Solid- Iodine, Astatine
• Liquid- Bromine
• Gas- Fluorine, Chlorine

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NOBLE GASES

• do not form compounds easily
• Very unreactive due to their octet

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Noble Gases
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Special elements

• Hydrogen and Helium are special b/c although they
  share some characteristics with their
  groups/families, they are different b/c they have
  properties that are not similar to those of ANY
  group
• Hydrogen and helium are the simplest and most
  abundant elements. Hydrogen makes up 76 of the
  mass of the universe and helium makes up 23

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

• Radius decreases across a period

Increased magnetic attraction

• 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

• Tends to increase across a period

Atoms become closer to a full electron octet in
the outer energy level

• Tends to decrease down a group

Outer electrons are farther from the nucleus
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Table of 1st Ionization Energies
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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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Another Way to Look at Ionization Energy
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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 (full octet)

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

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Periodic Table of Electronegativities
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Summation of Periodic Trends