Presentation on theme: "Periodic Trends You will know what ionization energy is and how it trends on the periodic table You will know what electron affinity and electronegativity."— Presentation transcript:
1 Periodic TrendsYou will know what ionization energy is and how it trends on the periodic tableYou will know what electron affinity and electronegativity are and how they trend on the periodic tableYou will know how cations and anions compare in size to their parent atoms
2 What Are Ions? Na+ Cl- NH4+ SO32- Ion Definition - An atom or group of bondedatoms that have a positive or negative chargeNa+Sodium cationCl-Chloride anionNH4+Ammonium cationSO32-Sulfite anionAny process that creates an ion is referred toas ionization.
3 Ionization Energy A + energy ------> A+ + e- The energy required to remove one electronfrom a neutral atom = ionization energyA + energy > A+ + e-For main group elements ….Ionization energy increases across each periodIonization energy decreases down each group
5 What determines IE?The greater the nuclear charge, the greater IE (for periods)Greater distance from nucleus decreases IE (for groups)
6 Electron Affinity A + e- ------> A- + energy The energy produced when an electronis added to neutral atom = electron affinityA + e > A- + energy
7 Electron Affinity Trend The energy release when an electron is added to an atom. Most favorable toward NE corner of PT since these atoms have a great affinity for e-.
8 Electronegativity Measure of how much an atom can attract electrons Higher electronegativity results in higher numberHighest value is FluorineLowest value is FranciumProposed by Linus Pauling --- Useful in describingproperties of compounds
10 Trends in Ionic Size (page 175-176 book) Cations are always smaller than the atoms they come from.Example: Na+ is smaller than NaAnions are always larger than the atoms they come from.Example: F- is larger than F