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Early periodic tables Dobereiner - early 1800s Triads- elements with similar properties Cl, Br, I Ca, Sr, Ba Newlands - 1865 62 known elements Law of Octaves (every 8 th element is similar)
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Mendeleev’s table - 1869 By atomic mass In columns Predicted missing elements
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Moseley’s table – 1910’s Working in Rutherford’s lab Arranged by positive charge he called atomic number In rows Died in WWI
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Periodic law When the elements are arranged by increasing atomic number, their physical and chemical properties show a repeating pattern
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ELEMENTS Metals left side of periodic table Nonmetals right side of periodic table Metalloids along diagonal line
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Metals Lose electrons to make + ions (cations) Conduct electricity Conduct heat Malleable Ductile React with acids Solids (except ?) Shiny
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Nonmetals Gain electrons to form – ions (anions) Do not conduct heat Do not conduct electricity Brittle Solids, liquids or gases Do not react with acids Dull
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Metalloids Properties of either Some gain, some lose electrons Some conduct, some don’t Some are malleable, some brittle All are solids
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Patterns of Atomic Numbers A-6 Family NameIonValence electron Alkali metals (H) +1 1 Alkaline earth(Be) +2 2 Aluminum (B) +3 3 Carbon+/-44 Nitrogen-35 Oxygen-26 Halogen(F)-17 Noble(He)08
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Trends Atomic radiusAtomic radius Melting pointMelting point ElectronegativityElectronegativity Oxidation number (charge on ion)Oxidation number (charge on ion)
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Atomic radius Size of the atom Down a family atoms get bigger due to more energy levels Across a periodAcross a period atoms get smaller due to more pull by protons on electrons
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1. Which is bigger Be or O? Why? Be 2.Which is bigger Li or K? Why? K 3.Which is smaller B or Al? Why? B 4. Which is smaller F or Cl? Why? F
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Atomic Size Li Na K Rb Cs H Ne Ar Kr Xe Rn
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Electronegativity the desire of an atom to steal another atoms electron Down a familyDown a family electronegativity get smaller Across a periodAcross a period electronegativity gets larger
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Electronegativity F Cl Br I He Ne Ar Kr Xe
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Oxidation Number Charge on the ion Metals Lose electrons – get smaller +1, +2, +3, +4 Non metals - get bigger gain electrons -3, -2, -1 -3, -2, -1
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Oxidation Number C Si CaSrBa N P Se I
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Melting Point Down a familyDown a family melting point gets smaller Across a periodAcross a period melting point gets larger
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Melting Point C Si Ca SrBa HeNe Ar Kr Xe
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What determines properties A - 7 Ionic Compounds Metal/nonmetal steal electrons +/- attraction strong High melting/boiling points Molecules Nonmetal/nonmetal share electrons Weak attraction Low melting/boiling points
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Periodic table A-4 Mendeleev 1869 Organized elements by increasing atomic mass (weight) in columns Predicted missing elements Today’s table Organized by increasing atomic number (protons) in rows
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1.Which has a smaller melting point N or P? P 2.Which has a smaller melting point Na or Mg? Mg 3.If the melting point of Si is o C and S is o C what would you expect the melting point of P to be?
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Octet Rule An atom will gain or lose electron to have an octet (or filled) valence energy level
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