Periodic Table -- Organization of Elements Mendeleev organized the elements based on their increasing atomic mass and their physical properties

Properties Determined by the # of e- in the outer energy level Same number in the outer shell = same group Example: Group 1 React explosively with water Properties

Valence electrons Outer shell electrons

Metals Good conductor of heat and electricity Luster (shiny) Malleable (turn into shapes)

Metals (cont) Ductile: stretched into wire Solid at room temp Exception : Hg (Mercury) is liquid at room temp Left of the zigzag - EXCEPT HYDROGEN

Non-metals Right of the zigzag, and hydrogen Lack luster Do not conduct heat or electricity Not ductile Not malleable Found as solid or gas Exception: Br (Bromine) on liquid non-metal Non-metals

Non-metals

Has properties of both Found along the zigzag Example Po (Polonium) Metalloids Has properties of both Found along the zigzag Example Po (Polonium)

Reactivity