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
  • \
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

    \     \     \

\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \

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

\ \