Periodicity Properties of elements Sizes of atoms and ions Electron Configuration of ions Ionization Energy Electron affinity Reactivity Metallic Character Mary J Bojan Chem 110 1 Electron Configuration and the Periodic Table Location on Periodic Table is related to electron configuration Elements in the same row family have the same valence shell configuration Example alkali metals row 1 have ns1 valence configuration H Li Na K Rb Cs 1s1 He 2s1 Ne 3s1 Ar 4s1 Kr 5s1 Xe 6s1 halogens F Cl Br I have Valence electrons determine the chemistry noble gases inert have Mary J Bojan Chem 110 2 PROPERTIES OF ELEMENTS Electron configurations determine the organization of the Periodic Table AND the properties of the elements reason for periodic trends in behavior Properties of elements are determined by Size n and shape of orbitals Atomic number nuclear charge Elemental properties atomic size ionization energy electron affinities reactivity Mary J Bojan Chem 110 3 ATOMIC SIZE size increases going down group WHY size decreases going from left to right across a period WHY Mary J Bojan Chem 110 4 Trends in Radii Mary J Bojan Chem 110 5 ELECTRON CONFIGURATIONS OF IONS Elements gain or lose electrons to form separate ions with complete octets eNa 1s2 2s2 2p6 3s1 Cl 1s2 2s2 2p6 3s23p5 core electrons valence electrons Na 1s2 2s2 2p6 Ne Mary J Bojan Cl 1s2 2s2 2p6 3s23p6 complete octets Ar Chem 110 6 Charges of Common Ions Mary J Bojan Chem 110 7 ION SIZES cations are smaller than parent atoms Na 1 86 anions are larger than parent atoms Cl 0 99 Na 0 96 Cl 1 81 atom size increases going down family ion size also increases Li Na K Rb Mary J Bojan F Cl Br I size increases Chem 110 8 Ionic Radii Mary J Bojan Chem 110 9 ISOELECTRONIC SERIES Isoelectronic Isoelectronic series a series of atoms or ions that have Example O2 F Na electrons nuclear charge size Mg2 Al3 Put these ions in order of increasing size Ca2 Mary J Bojan S2 K Cl Chem 110 10 IONIZATION ENERGY Energy needed to remove an electron I1 First ionization energy I1 I2 Second ionization energy I2 etc Mary J Bojan Chem 110 11 IONIZATION ENERGY Example Mg 1s22s22p6 3s2 Ne core electrons I1 I2 I3 Mary J Bojan 738 1451 7733 kJ mol kJ mol kJ mol valence electrons Mg g Ne 3s1 Mg 2 g Ne Mg 3 g 1s2 2s22p5 Chem 110 12 IONIZATION ENERGY Mary J Bojan Chem 110 13 IONIZATION ENERGY TRENDS going down a family Li Size Na K Rb Cs I1 kJ mol 510 490 I E 418 increases 403 375 across the periodic table Na Mg 490 735 size Al Si P S 580 780 1060 1005 Cl 1225 Ar 1550 I1 kJ mol I E I1 increases from left to right some exceptions Electron further from the nucleus easier to remove but takes extra energy to remove electrons from filled subshells Mg Ar or half filled subshells P Mary J Bojan Chem 110 14 Ionization Energy Mary J Bojan Chem 110 15 Trends in I E Mary J Bojan Chem 110 16 ELECTRON AFFINITIES Energy needed to add an electron to an atom or ion in the gas phase Cl g e Cl g E A 349kJ mol Halogens Group II metals Be Mg Ca Group I metals Noble gases Mary J Bojan Chem 110 17 Electron Affinities Mary J Bojan Chem 110 18 Metal vs Nonmetal Mary J Bojan Chem 110 19 METAL REACTIVITY 2Li s 2H2O 2Li aq 2OH aq H2 g 2Na s 2H2O 2Na aq 2OH aq H2 g 2K s 2H2O 2K aq 2OH aq H2 g Li Na K Rb Be Mg Ca Sr Reactivity as ionization energy IE energy need to form a positive ion Mary J Bojan Chem 110 20 HALOGEN REACTIVITY 2KCl aq Br2 aq 2KCl aq I2 aq 2KBr aq I2 aq 2KBr aq 2KI aq 2KI aq no reaction no reaction no reaction Cl2 aq 2KCl aq Br2 aq Cl2 aq 2KCl aq I2 aq Br2 aq 2KBr aq I2 aq Cl2 more reactive than Br2 or I2 Br2 more reactive than I2 F2 electron Cl2 reactivity affinity Br2 I2 Reactivity increases as electron affinity increases Mary J Bojan Chem 110 21
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