Periodic Table

 Developed by Dmitri Mendeleev  Elements in order of increasing atomic #

Arrangement  Metals on Left  Properties of metals: ductile, shiny, malleable, conductive.

Arrangement  Nonmetals on Right  Properties of nonmetals: dull, brittle, insulators Sulfur

Arrangement  Stair Step line of metalloids  Metalloids are materials that share properties of both metals and nonmetals  (ex. Brittle and shiny)  Includes the elements B, Si, Ge, As, Sb, Te

Periods  Horizontal rows  Characteristics change as you move across the period  Period # tells how many energy levels

Li

Groups/Families  Vertical columns  Elements in the same group have similar characteristics

Valence Electrons  Valence electrons determine REACTIVITY with other elements  They are involved in bonding.  Groups 1-2 & 13-18: the ones place of the group # represents the # of valence electrons  Ex. Group 1 has 1 Valence Electron  Ex. Group 13 has 3 Valence Electrons  Lewis Dot Structures show only the valence electrons around an atom.

Examples of Lewis Dot diagrams

Reactivity = Chemical Properties  Valence electrons determine how likely an atom is to react with another atom  Atoms want their valence orbital to be full  2 is considered full on first energy level  8 is considered full on 2 nd and 3 rd energy levels  Atoms that have full valence shells do not react with other atoms.

Group 1  1 valence electron  VERY Reactive  Lithium, Sodium, Potassium, Rubidium, Cesium, Francium  Shiny and soft enough to be cut with a knife, the alkali metals are usually white (though cesium is more of a yellowish white).  When placed in a flame, most of these substances produce characteristic colors: lithium, for instance, glows bright red, and sodium an intense yellow.

Lithium Sodium

Group 2  2 valence electrons  Less reactive than Group 1  They are silvery, shiny, and relatively soft metals

Group 3-12  Transition Metals  Shiny, good conductors of heat & electricity  Less reactive than groups 1 & 2  Includes the radioactive Lanthanides & Actinides

Group  Includes Metals, Metalloids (B, Si, Ge, As, Sb, Te) & Nonmetals  Same number of valence electrons as ones place of group #

Group 17  Halogens  Most reactive nonmetals  7 valence electrons  The term "halogen" means "salt-former" and compounds containing halogens are called "salts".  The halogens exist, at room temperature, in all three states of matter:  Solid - Iodine, Astatine  Liquid - Bromine  Gas - Fluorine, Chlorine

Group 18  Noble Gases  Unreactive nonmetals – colorless, odorless gases  Outer energy level is full  Helium, Neon, Argon, Krypton, Xenon, Radon

Hydrogen  Nonmetal that fits no other group  It is often included above group 1 b/c it has 1 valence electron