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