THE PERIODIC TABLEM. Peverill

HISTORY OF THE PERIODIC

TABLE

• 1817 - Johann Dobereiner, Law of Triads

• 1862 - A. E. Beguyer de Chancourtois, First attempt

at a periodic table

• 1863 - John Newlands, Law of Octaves

• 1864 - Lother Meyer, abbreviated version of Periodic

Table. He published the extended version in 1870.

Unfortunately for him…

• Published his Periodic Table

in 1869.

• More easily predicted new or

missing elements.

Mendeleev predicted 10 new

elements, 7 of which existed.

DMITRI MENDELEEV

Columns = Groups

Rows = Periods

• Group = Number of valence electrons

• Period = Number of orbitals

METALS

PROPERTIES OF METALS

• Form cations (positive ions)

• Good conductors

• Lustrous (shiny)

• Malleable

• Solid at room temp. (except for mercury)

NON-METALS

PROPERTIES OF NON-

METALS

• Form anions (negative ions)

• Poor conductors

• Solid forms are brittle, group 17 and 18 are

gases at room temp. (except for bromine)

METALLOIDS

PROPERTIES OF

METALLOIDS

• “Staircase” elements

• Appear metallic but are brittle

• Semi-conductors

• Metal + Metal = Alloy

• Metal + Non-Metal = Ionic Compound (salt)

• Non-Metal + Non-Metal = Molecular

Compound

ALKALI METALS

ALKALI METALS

• Group 1 = 1 valence electron

• Form cations with +1 charge

• Most reactive metals

• Do not exist purely in nature

ALKALINE EARTH METALS

ALKALINE EARTH METALS

• Group 2 = 2 valence electrons

• Form cations with +2 charge

• Less reactive than Group 1 metals

• Found as salts in nature (metal + halogen)

TRANSITION METALS

TRANSITION METALS

• Form cations just like other metals, but have

multiple oxidation states (can have different

charges).

• Exceptions: Ag and Zn

HALOGENS

HALOGENS

• Group 17 = 7 valence electrons

• Form anions with -1 charge

• Most reactive elements

NOBLE GASES

NOBLE GASES

• Group 18 = 8 valence electrons

• Full valence shell (stable octet), therefore they

do not react

• Gases at room temp.

• Atomic Number (# of protons)

• Element Symbol

• Element Name

• Atomic Mass (average mass of isotopes)

REFERENCES

• Searle, S. (2011) Nova Scotia Science 10.

McGraw-Hill Ryerson

• http://www.wou.edu/las/physci/ch412/perhist.

htm