The Periodic Table

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The Periodic Table

• Ch.4

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(4-1) Johann Dobereiner

• Law of Triads groups of 3 elements w/ similar
  properties

Li
Na
K
Ca
Sr
Ba
Cl
Br
I
3
John Newlands

• Inc. atomic mass
• Law of Octaves properties repeated w/ the 8th
  element

Li Be B C N O F
Na Mg Al Si P S Cl
4
Dmitri Mendeleev

• Modern periodic system
• Inc. atomic mass
• Elements of similar properties fall in vertical
  columns
• Dont always fit in inc. mass (Te, I)
• Gaps where particular mass should fit

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Henry Moseley

• Arranged elements in order of inc. atomic

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Periodic Law

• Properties of elements are periodic functions of
  their atomic s
• Regular repeating pattern

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Periods Groups

• Period horizontal row
• Similar e- config.
• Group (family) vertical column
• Similar properties

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Metals

• Metal good conductor of electricity
• Transition metals
• d f-block
• Not as reactive as Gr.1 2

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Nonmetals Metalloids

• Nonmetal poor conductor of electricity
• Some of p-block
• Semiconductor (metalloid) conduct electricity,
  but not well
• Along stair-step (B, Si, Ge, As, Sb, Te)

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Main Group Elements

• Representative elements
• Regular e- config.
• s- p-block

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Gr.1 Alkali Metals

• Very reactive metals
• 1 e- in highest E level
• Burn in air
• Extremely soft

12
Plasma

• 4th state of matter
• Mixture of particles that conducts electricity

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Gr.2 Alkaline-Earth Metals

• Reactive metals (less than Gr.1)
• 2 e- in outer E level
• Harder stronger than Gr.1

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Lanthanides

• Shiny transition metals

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Actinides

• Shiny transition metals
• Radioactive (unstable nucleus)

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Gr.13 Boron Family

• Metalloid metals
• Al used to be rare expensive

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Gr.14 Carbon Family

• Elements impt. to life (C) computers (Si Ge)

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Gr.15 Nitrogen Family

• N2 makes up ¾ of atmosphere
• N P impt. to life

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Gr.16 Oxygen Family

• O2 necessary for respiration
• Many stinky things contain S (rotten eggs,
  garlic, skunks)

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Gr.17 - Halogens

• Most reactive of nonmetals
• 7 e- in the outer E level
• Combine w/ metals to form salts
• Ex K Cl- ? KCl
• Salt - ions arranged in a regular 3-D
  pattern (crystal)

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Gr.18 Noble Gases

• Very low reactivity
• Very stable
• 8 e- (octet) in outer E level

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Hydrogen

• Most common element
• Reacts w/ many elements
• Alternative fuel source

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(4-2) Characteristics of Metals

• Shiny (luster)
• Good conductors
• e- free to move through a metal in all directions
• Sea of e-

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Characteristics of Metals

• Ductile drawn into a wire
• Malleable hammered or rolled into sheets
• Alloy solid or liquid soln of 2 or more metals
  or sometimes nonmetals

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Symbols

• Metals will be in a crystal form attached to many
  other metal atoms
• Monatomic symbols Fe, Hg,etc.

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(4-3) Periodic Trends

• Bond radius ½ the dist. from the center of 2
  like atoms bonded together

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Atomic Radius

• Inc. down a group
• Add extra E levels
• e- shielding reduction of attractive force b/w
  a nucleus outer e- due to cancellation of
  some charge by inner e-
• Dec. across a period
• Inc. charge of nucleus pull e- closer

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Ionic Radius

• Ions arent the same size as the atoms they come
  from
• ions are smaller
• Lose layers of e-
• - ions are larger
• Gain layers of e-

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Ionization Energy

• Amt of E needed to remove an outer e- in its
  ground state
• Inc. across a period
• charge inc. which holds e- more tightly
• Dec. down a group
• Outer e- farther from nucleus

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Electron Affinity

• Ability of an atom to attract hold an e-
• More negative across a period
• charge inc. attraction to e- inc.
• Dec. down a group
• Shielding offsets charge attraction to e- dec.

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Melting Boiling Points

• mp bp reach their max when d p orbitals are ½
  full then dec. again

p
d
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(4-4) Big Bang

• 12-16 bya entire universe fit on pinhead
• Exploded, but Ts were so hot only E existed
• Expanded, cooled, atoms formed
• Clouds of H accumulated gravity pulled them
  closer together inc. P T forming stars

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Natural Elements

• In hot center of stars, nuclear rxns took place
• Nuclear rxn change in the composition of the
  nucleus of an atom
• Fusion
• The higher the T, the larger the element formed
• 93 naturally occurring elements

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Synthetic Elements

• Transmutation changing 1 nucleus into another
  by radioactive disintegration or bombardment w/
  other particles

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Cyclotron Synchrotron

• Cyclotron accelerates charged particles to very
  high E
• Forces fusion
• Synchrotron times impulses to match
  acceleration of particles
• Used for superheavy elements