What is the periodic table? compact way of organizing elements contains lot of information allows one to make predictions about behavior & properties of elements Elements

History of the Periodic Table End of 1700’s – less than 30 elements known Many elements discovered during 1800’s

John Newlands 1864: Law of Octaves elements arranged by atomic mass their properties repeat every 8th element Law of Octaves did not work for all known elements Key idea was correct: Properties of elements do repeat in periodic way

Mendeleev & Meyer 1869: Mendeleev produced 1st accepted PT elements ordered by ↑ atomic mass into columns with similar properties Predicted existence & properties of undiscovered elements Not totally correct more accurate atomic mass calculations showed some elements not in right place

Remember 1860’s: No subatomic particles yet discovered Dalton’s billiard ball model of the atom

1913 – Henry Moseley By 1913, protons & electrons discovered neutrons were predicted determined atoms of each element contain unique # protons (= atomic number) rearranged Mendeleev’s PT by atomic # instead of atomic mass problems with elements in wrong place disappeared

Periodic Law periodic repetition of chemical & physical properties of elements when are arranged by ↑ atomic number

Glenn Seaborg: 1950’s Lanthanide and Actinide Series

Newlands Seaborg Mendeleev Mosley

Vocabulary of the PT

Columns called groups or families Today: #1 thru 18, Arabic numerals Past: A & B groups, Roman numerals A-Group Columns 1,2,13-18 # IA – 8A B-Group Transition metals (columns 3-12) # IB - 8B

Rows called series or periods #1 thru 7

Column numbering (1  18) left to right Period numbering (1  7) top to bottom

Structure of the Periodic Table Closely related to electron configuration

Energy Levels = Row Number Elements in same row have same # of energy levels # of principal energy levels = to row #

Going Across Row 2: 2-8 Ne 18 (VIIIA) 2-7 F 17 (VIIA) 2-6 O 16 (VIA) 2-5 N 15 (VA) 2-4 C 14 (IVA) 2-3 B 13 (IIIA) 2-2 Be 2 (IIA) 2-1 Li 1 (IA) Configuration Element Family

Going Down Column 1: 2-8-18-32-18-8-1 Fr 7 2-8-18-18-8-1 Cs 6 2-8-18-8-1 Rb 5 2-8-8-1 K 4 2-8-1 Na 3 2-1 Li 2 1 H Configuration Element Period

Number of Valence Electrons Elements in same column have same # valence electrons 4 14 or IVA 3 13 or IIIA 2 2 or IIA 1 1 or IA Number of Valence Electrons Group

Valence Electrons Chemical behavior determined by # valence electrons Elements with same # valence electrons have similar chemical properties Elements in same column have similar chemical properties

Classifying the Elements 2/3 of elements are metals Remaining are non-metals and metalloids (semi-metals) Metalloids have some properties of metals & some properties of nonmetals Staircase: dividing line between metals & nonmetals elements to left are metals (except H) elements to right are non-metals

Properties of Metals malleable – pounded into sheets ductile – drawn into wires have Luster good conductors of heat & electricity solid at room temperature (except Hg) metals lose electrons to form positive ions “Metals are losers” Low ionization energy Low electronegativity

Properties of Nonmetals gas or solid (except Br2) solids are brittle solids are dull poor conductors of heat & electricity nonmetals gain electrons & form negative ions “Nonmetals are winners” High ionization energy High electronegativity Properties are OPPOSITE of metals

Properties of Metalloids 5 on right side staircase: B,Si,As,Te,At 2 on left side staircase: Ge,Sb Each metalloid has some metallic and some nonmetallic properties Example:Si shiny like metal but brittle like nonmetal

Names of Families (AKA group A elements) Group 1 = Alkali Metals Group 2 = Alkaline Earth Metals Group 13 = Boron family Group 14 = Carbon family Group 15 = Nitrogen family Group 16 = Oxygen family Group 17 = Halogens Group 18 = Noble Gases

Transition Metals Groups 3 through 12 AKA group B elements Actinide and Lanthanide series = inner transition elements Transition elements put the COLOR in your life form brightly colored salts/solutions

Elements that are gases at STP Diatomics: H2, N2, O2, F2, Cl2 Monatomics: noble gases He, Ne, Ar, Kr, Xe, Rn

Elements that are liquids at STP Br2 (non-metal) and Hg (metal)

All other elements are solids at room temperature