Periodic Table

How it's organized

Periodic TableBy: Henna Aman

Describe the handout on this blackboard...

Changing the Arrangement-45 years later, a British scientist named Henry Moseley discovered that all elements fit on the periodic table when arranged by atomic number.

The History Behind the Table- periodic means repeating-the table was created by Dmitri Mendeleev, a Russion chemist- he arranged the table in order of increasing atomic mass

Dmitri Mendeleev{Atomic mass}

Henry Moseley{atomic number}

-each horizontal row is called a period (7)-elements in the same period have the same number of electron shells-each vertical row is called a group (18)-elements become less metallic as you move to the right

TYPES OF ELEMENTS

METALLOIDS-found onthe zig-zag line-half full outer cloud-shiny or dull-semi-conductor

METALS -found to the left-almost empty outer cloud-malleable, good conductors,ductile, shiny

NONMETALS-found to the right-almost full outer clouds-brittle, poor conductors

-GROUP 1- alkali ; 1 valence electron, very reactive, low density-Group 2- alkaline-earth metals; very reactive, 2 outer electrons, more dense, silver colorGroup 3-12- transition metals; all metals, 1 or 2 valence electrons, reactive, properties of metals. also include lanthanides & actinides-Groups 13-16- metalloids; 3 outer electrons, reactive-Group 17- hallogen; 7 outer electons, very reactive-Group 18- noble gases; 8 outer electrons, unreactiveHydrogen stands apart;l 1 outer electron, reactive, behaves like a nonmetal