The Periodic Table and Mendeleev

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The Periodic Table

In 1896 Dmitri Mendeleev arranged the known elements ...

in order of increasing atomic mass

And elements where sorted into groups of similar properties (underneath each other)

Mendeleev then used his table to predict the elements yet to be discovered and their properties. He did this by leaving gaps in his table for the missing elements and looked at the properties around the gaps to acurately predict the unknown elements traits.

Such as Melting Point, Appearance, Atomic Mass, Density and Formulas

Look at Diagram to the left of modern periodic table

Elements are arranged in order of increasing atomic number in rows called periods

Elements with similar Properties are placed in the same vertical cloumn called groups

alkali metals: Very reactive (needs one positive charge to react)

alkali earth metals: slighlty less reactive then alkali metals (need two positive charges to react)

Transition metals: typical metals, unreactive, good conductors of heat and electricity and are malleable

Halogens: Extremly reactive gases that form negative ions (next to Noble gases)

Rare eath metals: Hard to react with one another

Noble Gases: Completely unreactive

ALL metals are found on the left hand side (stopping after the poor metals on the diagram) while all non metals are on the right hand side.