What is the periodic table? compact way of organizing elements contains a lot of information allows us to make predictions about behavior and properties of elements based on their positions in PT Element Song

History of the Periodic Table end of 1700’s – less than 30 elements known many elements discovered during 1800’s many experiments done to determine atomic masses of the new elements

John Newlands 1864: if arrange elements by atomic mass – properties: repeat every 8 th element Law of Octaves –did not work for all known elements Key Idea was correct: properties of elements do repeat in periodic manner

Mendeleev & Meyer 1869: Mendeleev produced 1 st accepted PT – elements: in columns according to ↑ atomic mass – elements with similar properties grouped together predictedpredicted existence & properties of undiscovered elements not totally correct –more accurate atomic mass calculations showed some elements were not in right place

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

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

Periodic Law increasing atomic number There is a periodic repetition of the elements chemical and physical properties if they are arranged by increasing atomic number

Glenn Seaborg: 1950’s Lanthanide and Actinide Series

Seaborg Mendeleev Mosley Newlands

Classifying the Elements metals2/3 (75%) of elements are metals non-metals metalloidsremaining elements: non-metals & metalloids (semi-metals) metalloids: –have properties of both metals & non-metals staircase:staircase: –dividing line between metals & non-metals –elements to left are metals (except H) –elements to right are non-metals

Vocabulary of PT groupsfamiliescolumns called groups or families –today: #1 thru 18, Arabic numerals –past: A & B groups, Roman numerals A-Group (tall columns) –columns 1,2,13-18 (= representative elements) –IA – 8A B-Group (short columns) –transition metals (columns 3-12) –IB - 8B seriesperiodsrows are called series or periods –#1 thru 7

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

Names of Families AKA: A group 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 AKA B group elements Groups 3-12: Transition metals

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

Elements that are gases at STP Diatomics: H 2, N 2, O 2, F 2, Cl 2 Monatomics: noble gases He, Ne, Ar, Kr, Xe, Rn

Two elements are liquid at room temperature Br 2 (non-metal) and Hg (metal)

All other elements are solids at room temperature

Structure of Periodic Table closely related to electron configuration of each element

Energy Levels = Row Number elements in same row have same # of principal energy levels –so # of principal energy levels = to row #

Going Across Row 2: 2-8Ne18 (VIIIA) 2-7F17 (VIIA) 2-6O16 (VIA) 2-5N15 (VA) 2-4C14 (IVA) 2-3B13 (IIIA) 2-2Be2 (IIA) 2-1Li1 (IA) ConfigurationElementFamily

Valence Electrons chemical behavior determined by # valence electrons elements with same # valence electrons will have similar chemical properties –elements in same column have similar chemical properties

Going Down Column 1: Fr Cs Rb K Na3 2-1Li2 1H1 ConfigurationElementPeriod

Valence Electrons 414 or IVA 313 or IIIA 22 or IIA 11 or IA Number of Valence Electrons Group

PROPERTIES of the Elements

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

Properties of Non-metals generally gases or solids (except Br 2 ) solids are brittle solids are dull poor conductors of heat & electricity non-metals gain electrons & form negative ions “Non-metals are winners” “Non-metals are winners” high ionization energy high electronegativity

Properties of Metalloids 7 metalloids: –5 on right of staircase: B,Si,As,Te,At –2 on left of staircase: Ge,Sb Each metalloid has some metallic and some non- metallic properties example: Si shiny like metal but brittle like non-metal