Organization of the Periodic Table

Who is Mendeleev? Scientist who first developed a Periodic Table 1869 based arrangement on chemical and physical properties of elements known at the time

Protons & the Atomic Number the number of protons in an atom Determines the identity of the element each element has its own unique atomic # increases as you move left to right in the Periodic Table Always top # Identifies element # of protons for that atom only 6 C 12 Carbon

Periods rows going across the Periodic Table Periods (the rows) are based on # of electron energy levels atomic number increases by 1 as you move to each element in period properties of the elements change in predictable patterns across the period

Ta Da! The Periodic Table! Period 1: 1 e- level Period 2: 2 e- levels

Groups columns going down the Periodic Table also called Families Groups (the columns) are based on the elements having similar properties (all elements in each group have similar properties)

Ta Da! The Periodic Table! Group 1 = Alkali Metals (most reactive) 1 valence electron Group 17 = Halogens (combine to form salts) 7 valence electrons Group 2 = Alkaline Earth Metals 2 valence electrons Groups 13-16 = BCNO group 3-6 valence electrons H Groups 3-12 =Transition Metals # electrons varies He Be B C N O F Group 18 = Nobel Gases (least reactive) 8 valence electrons La Lanthanides & Actinides - Many are radioactive, also called rare earth metals Ac Ta Da! The Periodic Table!

Group Names Group 1 = Alkali Metals (most reactive) 1 valence electron Group 2 = Alkaline Earth Metals 2 valence electrons Groups 3-12 =Transition Metals # electrons varies Groups 13-16 = BCNO group 3-6 valence electrons Group 17 = Halogens (combine to form salts) 7 valence electrons Group 18 = Nobel Gases (least reactive) 8 valence electrons Lanthanides & Actinides - Many are radioactive, also called rare earth metals

Use physical and chemical properties to classify an element as a metal Metals Use physical and chemical properties to classify an element as a metal Physical properties of metals: Hardness Luster = shiny Malleability = ability to be pounded into sheets or shapes Ductility = ability to be stretched into wire Conductors of heat and electricity Some have magnetism

Metals (cont.) Chemical properties of metals: Different levels of reactions; some highly reactive, others nonreactive Location in the periodic table: To the left of the “zigzag” line Lanthanides and Actinides

Nonmetals Use properties to classify elements as a nonmetal Physical properties of nonmetals: Opposite of metals Dull Brittle Poor conductors Chemical properties: Different levels though generally less reactive than metals Readily form compounds

Nonmetals (cont.) Location in the periodic table: To the right of the “zigzag” line and Hydrogen

Metalloids Have varying properties of both metals and nonmetals Location in the periodic table: 7 of the elements around the “zigzag” Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, and Astatine