The Periodic Table

most of the pure elements are solid at room temperature, only 11 naturally occurring elements are a gas, and only 2 elements are liquid at room temperature

Dmitri Mendeleev ( ) organized a “Periodic Table” (only knew about 63 elements at the time) based on increasing atomic mass –the properties of elements had something to do with their mass even left empty spaces to be filled in later

Main “categories” of elements

Metals –shiny –ductile –malleable –good conductors of heat and electricity –have high melting points –will corrode (rust) in water or air –generally give away electrons

Nonmetals or gases –located to the right of the zig-zag line in the periodic table –often are different from one another –dull –do not conduct heat and electricity –are not malleable nor ductile –have a tendency to gain electrons

Metalloids –elements on the “zig-zag line” –have some characteristics of both metals and nonmetals

Groups are the vertical columns. –elements have similar, but not identical, properties most important property is that they have the same # of valence electrons

Alkali Metals most reactive of the metals because they all lose one valence electron VERY easily soft metals

Alkaline Earth Metals harder and denser than alkali metals not as reactive as the alkali metals

Transition Metals (Elements) display typical metallic characteristics can share or give away valence electrons depending what they chemically combine with

Halogens form diatomic molecules –(F 2 Br 2 I 2 Cl 2 ) all gain one valence electron VERY easily

Noble Gases mostly unreactive because their valence level is full (2,8,8….) colorless, odorless gases

Mixed Groups not as similar to each other as other groups usually named after the first element in the group (B C N O)

Rare Earth Elements many are synthetically produced (not actually rare) have been separated from the others to make the table not as wide used in the nuclear industries, metallurgy, ceramics, electrical components…

Periods are the horizontal rows –do NOT have similar properties –however, there is a pattern to their properties as you move across the table