The Periodic Table

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The Periodic Table
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Why is the Periodic Table important to me?

• The periodic table is the most useful tool to a
  chemist.
• You get to use it on every test.
• It organizes lots of information about all the
  known elements.

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Pre-Periodic Table Chemistry

• was a mess!!!
• No organization of elements.
• Imagine going to a grocery store with no
  organization!!
• Difficult to find information.
• Chemistry didnt make sense.

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Dmitri Mendeleev Father of the Table

• HOW HIS WORKED
• Put elements in rows by increasing atomic weight.
• Put elements in columns by the way they reacted.

• SOME PROBLEMS
• He left blank spaces for what he said were
  undiscovered elements. (Turned out he was
  right!)
• He broke the pattern of increasing atomic weight
  to keep similar reacting elements together.

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The Current Periodic Table

• Mendeleev wasnt too far off.
• The horizontal rows are called periods and are
  labeled from 1 to 7.
• The vertical columns are called groups are
  labeled from 1 to 18.
• Now the elements are put in rows by increasing
  ATOMIC NUMBER!!
• There is a periodic repetition of their physical
  chemical properties when elements are arranged
  by their atomic numberthis is called The Modern
  Periodic Law.

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GroupsHeres Where the Periodic Table Gets
Useful!!

• Elements in the same group have similar chemical
  and physical properties!!
• (Mendeleev did that on purpose.)

• Why??
• They have the same number of valence electrons.
• They will form the same kinds of ions.

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METALS

• More that ¾ of the known elements are metals.
  Metals share similar properties
• Good conductors of heat electricity
• Luster
• Malleable ductile
• High densities
• High boiling points melting points
• Resists stretching twisting
• Solids at room temperature

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NONMETALS

• No luster
• Poor conductors
• May be solid, liquid or gas
• Low densities
• Low melting boiling points

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METALLOIDS

• Also called semimetals
• Have properties of both metals and nonmetals

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Families on the Periodic Table

• Columns are also grouped into families.
• Families may be one column, or several columns
  put together.
• Families have names rather than numbers. (Just
  like your family has a common last name.)

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Hydrogen

• Hydrogen belongs to a family of its own.
• Hydrogen is a diatomic, reactive gas.
• Hydrogen was involved in the explosion of the
  Hindenberg.
• Hydrogen is promising as an alternative fuel
  source for automobiles

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• German airship (called a zeppelin)
• 804 feet long
• In 1937 it caught fire killing 35 of the 97
  people on board.
• Travelling from Germany to US caught fire as it
  was landing in NJ
• LZ 129 Hindenburg was a German zeppelin. Together
  with its sister-ship LZ 130 Graf Zeppelin II it
  was the largest aircraft ever built.

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• LZ 129 Hindenburg was a German zeppelin. Together
  with its sister-ship LZ 130 Graf Zeppelin II it
  was the largest aircraft ever built.

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• A Zeppelin is a type of dirigible, more
  specifically a type of rigid airship

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• An airship is a buoyant aircraft that can be
  steered and propelled through the air. Unlike
  aerodynamic craft (e.g. airplanes and
  helicopters) which stay aloft by moving an
  airfoil through the air in order to produce lift,
  aerostatic craft such as airships (and balloons)
  stay aloft primarily by means of a cavity
  (usually quite large) filled with a gas of lesser
  density than the surrounding atmosphere.

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• In the early days of airships, the primary
  lifting gas was hydrogen. Until the 1950s, all
  airships, except for those in the United States,
  continued to use hydrogen because it offered
  greater lift and was cheaper than helium.

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Alkali Metals

• 1st column on the periodic table (Group 1) not
  including hydrogen.
• Low densities melting points
• React with oxygen moisture in air
• Most reactive metals, always combined with
  something else in nature, they are not found
  uncombined (like salt)
• Soft enough to cut with a butter knife
• Will react violently with water are stored
  under oil or kerosene

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Alkaline Earth Metals

• Second column on the periodic table. (Group 2)
• Reactive metals that are always combined with
  nonmetals in nature.
• Several of these elements are important mineral
  nutrients (such as Mg and Ca
• Harder than alkali metals
• Less reactive than alkali metals, not stored
  under oil or kerosene

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Transition Metals

• Elements in groups 3-12
• Less reactive harder metals
• Includes metals used in jewelry and construction.
• Metals used as metal.

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Boron Family

• Elements in group 13
• Aluminum metal was once rare and expensive, not a
  disposable metal.

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Carbon Family

• Elements in group 14
• Contains elements important to life and
  computers.
• Carbon is the basis for an entire branch of
  chemistry.
• Silicon and Germanium are important
  semiconductors.

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Nitrogen Family

• Elements in group 15
• Nitrogen makes up over ¾ of the atmosphere.
• Nitrogen and phosphorus are both important in
  living things.
• Most of the worlds nitrogen is not available to
  living things.
• The red stuff on the tip of matches is phosphorus.

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Oxygen Family

• Elements in group 16
• Oxygen is necessary for respiration.
• Many things that stink, contain sulfur (rotten
  eggs, garlic, skunks,etc.)

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Halogens

• Elements in group 17
• Very reactive, volatile, diatomic, nonmetals
• Always found combined with other element in
  nature .
• Form salts when combined with Groups 1 or 2
  metals
• Used as disinfectants and to strengthen teeth.

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The Noble Gases
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The Noble Gases

• Elements in group 18
• VERY unreactive, monatomic gases
• Occur in atmosphere in very small amounts
• Used in lighted neon signs
• Used in blimps to fix the Hindenberg problem.
• Have a full valence shell.

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• TRENDS IN THE PERIODIC TABLE

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• 1 ATOMIC SIZE
• The size of an atom is generally given in terms
  of
• the atomic radius.

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• GROUP TRENDS
• Atomic size generally increases as we move down a
  group.
• As we descend, electrons are added to
  successively higher energy levels.

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• PERIOD TRENDS
• Atomic size generally decreases as we move from
  left to right across a period.
• As we move across a period, electrons are added
  to the same energy level.

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• Protons are also added to the nucleus. The effect
  of the increasing nuclear charge on the outermost
  electrons is to pull than closer to the nucleus.
  Atomic size, therefore decreases.

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• 2 IONIZATION ENERGY
• The amount of energy required to remove an
  electron from an atom.

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• When the outermost electron is located close to
  the nucleus, there is a greater attraction
  between the positive protons (in the nucleus) and
  the negative electrons.
• Because of this, more energy is required to
  remove an electron.

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• When the outermost electrons are further from the
  nucleus, the attractive force is less, and it is
  easier to remove an electron.
• Therefore, the smaller the atom, the higher the
  ionization energy.

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• GROUP TRENDS
• Ionization energy decreases as we go down a group
• PERIOD TRENDS
• Ionization energy increases as we go across a
  period

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• 3 ELECTRON AFFINITY
• The amount of energy released when an electron is
  added to an atom.

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• When electrons are added close to the nucleus,
  there is a greater attraction between the
  negative electron and the positive nucleus and
  electron affinity is higher.
• Therefore, the smaller the atom, the higher the
  electron affinity.

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• GROUP TRENDS
• Electron affinity generally decreases as we go
  down a group
• PERIOD TRENDS
• Electron affinity generally increases as we go
  across a period.

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• 4 IONIC SIZE
• The size of an ion.

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• Metals low ionization energy form positive ions
  easily
• Nonmetals. high ionization energy form negative
  ions easily

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• CATIONS are always smaller than the neutral atom
• Atom loses outer shell electron
• Increased attraction of nucleus on remaining
  electrons

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• ANIONS are always larger than the neutral atom
• Nuclear attraction is less for the increased
  number of electrons
• Additional electrons also increases the repulsive
  forces between electrons

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• GROUP TRENDS
• Ionic size generally increases as we go down a
  group
• PERIOD TRENDS
• Ionic size generally increases for anions
• And decreases for cations
• as we go across a period left to right.

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• 5 ELECTRONEGATIVITY
• Describes an atoms ability to attract electrons.
  This trend is similar to electron affinity.

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• GROUP TRENDS
• Electronegativity generally decreases as we go
  down a group
• PERIOD TRENDS
• Electronegativity generally increases as we go
  across a period.

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• EXCEPTIONS.
• Nobel gases are not included in this general
  trend.

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CHEMISTRY NEGATIVITY

• The feeling you have the day after a Chemistry
  term Test!