The Periodic Table

Creators

• Döbereiner (1857) - triads
  • Ca, Sr, Br
• Newlands (1863) - arranged by increasing at. mass
  • Noted repetition of properties every 8th element
  • Law of Octaves - seven groups of 7
• Mendelev (1865) - First periodic table
  • Arranged by increasing at. mass
  • Left spaces for undiscovered elements
  • Noted recurring physical changes
• Mosely (1913) - arranged by increasing at. number
  • Found nuclear charge
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Groupings

• Period/Series - horizontal rows

  • Row number tells the outer Energy level of the element
  • Same number of Energy levels

• Group/Family - vertical columns

  • Similar physical and chemical properties

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Families

• 1A to 8A - Representative Elements
  • Same number of valence electrons
  • Similar electron configurations

1A Alkali Earth Metals

• Doesn't include H
• Most reactive metals
• 1 valence electron
• Low density, low melting point'
• Good conductivity
• Soft, shiny metals
• Very malleable, ductile
• Combine with H2O to form a strong base
• Explode in H2O
  • Exothermic reaction
  • Heat explodes Hydrogen

2A Alkaline Earth Metals

• 2 valence electrons
• Higher density than 1A
• Good conductivity
• Gray/white
• rapid oxidation
• Used in structural materials

6A Chalogen Family

• Also called Oxygen Family
• 6 valence electrons
• gain electron
  • forms anion

7A Halogens

• 7 valence electrons
• Always combined in nature

8A Noble Gases

• Unreactive
• 8 valence electrons
  • He has 2 electrons
• full outer E levers
  • S and P are full

Types of Elements

Metals

• left of zigzag; few outer electrons
• Tend to lose electrons (cation)
• Hard, shiny, malleable, good conductors
• Metal reactivity increases down and to the right

Nonmetals

• Right of zigzag; many outer electrons
• tend to gain electrons
• brittle solids, insulators, dull
• nonmetal reactivity increases up and to the right

Metalloid

• touching zigzag on a side
• characteristics of metals and nonmetals
• Doesn’t include Aluminum

Promotion

• Chromium Family
  • Cr - Chromium
  • Mo - Molybdenum
  • W - Tungsten
• Precious Metals
  • Cu - Copper
  • Ag - Silver
  • Au - Gold
• Fill partially filled sub level to become half filled
  • More stable

Oxidation Numbers

• Octet Rule - atoms with 8 outer electrons are stable
  • elements try to reach this
  • oxidation numbers - apparent changes elements have when they react
• All Transition Metals are +2
  • fill d sub level

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