205 Chemistry Notes 1

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Periodic Table

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205 Chemistry Notes 1

  1. 1. Chapter 15 Structure of the Periodic Table
  2. 2. patterns in the Periodic Table <ul><li>elements are arranged in order of increasing proton number; proton number increases from left to right across the Table </li></ul><ul><li>consists of: </li></ul>the Periodic Table <ul><li>periods: horizontal rows numbered 1, 2, 3, etc </li></ul><ul><li>groups: vertical columns labelled I, II, III, etc </li></ul><ul><li>transition elements </li></ul><ul><li>lanthanides & actinides (not tested) </li></ul>
  3. 3. patterns in the Periodic Table the Periodic Table
  4. 4. <ul><li>elements in the same group have the same number of valence electrons; form the same type and number of bonds </li></ul>patterns in the Periodic Table electronic structures and chemical bonds <ul><li>elements in the same group have similar chemical properties, and will react with other elements/compounds in the same way </li></ul><ul><li>Na + H 2 O  NaOH + H 2 </li></ul><ul><li>K + H 2 O  KOH + H 2 </li></ul>2.8.8.1 K potassium 2.8.1 Na sodium 2.1 Li lithium 2.4 C carbon 2.8.4 Si silicon Element Symbol Electron Configuration
  5. 5. patterns in the Periodic Table electronic structures and chemical bonds <ul><li>elements on the left side of the Periodic Table lose all their outer shell electrons to form positive ions </li></ul><ul><li>those on the right side gain electrons to fill their outer shells with eight electrons like a noble gas, forming negative ions </li></ul>- IV Si P 3- V P S 2- VI S Cl - VII C l Mg 2+ II Mg A l 3+ III A l - Na + Formula of Ion 0 I Group Number Element Na Ar
  6. 6. <ul><li>metals are found on the left side of the Periodic Table; non-metals are found on the right side </li></ul><ul><li>dividing line in the Periodic Table separates the metals and the non-metals </li></ul><ul><li>across each period from left to right, elements change from metals to non-metals </li></ul><ul><li>across each period, oxides of elements change from basic to acidic; elements near the dividing line form amphoteric oxides </li></ul><ul><li>in general, elements with small number of valence electrons are metals; elements with large number of valence electrons are non-metals </li></ul>patterns in the Periodic Table metals and non-metals
  7. 7. patterns in the Periodic Table metals and non-metals
  8. 8. <ul><li>proton number increases down a group </li></ul><ul><li>physical properties of elements change down a group </li></ul>patterns in the Periodic Table changes in a group <ul><li>For example: </li></ul><ul><li>Group I metals’ melting and boiling points decrease down the group </li></ul><ul><li>However, </li></ul><ul><li>Group VII halogens’ melting and boiling points increase down the group </li></ul>
  9. 9. using the Periodic Table predicting properties <ul><li>properties of elements can be predicted from knowledge of other elements in the same group </li></ul><ul><li>For example: </li></ul><ul><li>Chlorine reacts with sodium to form NaCl </li></ul><ul><li>Iodine, Bromine and fluorine also reacts with sodium to form NaI, NaBr and NaF </li></ul><ul><li>In reverse, we can also predict how potassium will react with chlorine </li></ul><ul><li>Qn: Predict the chemical formula of caesium iodide </li></ul>I 2 iodine Br 2 bromine C l 2 chlorine Element Molecular Formula
  10. 10. using the Periodic Table predicting properties <ul><li>properties of elements change from a group, with increasing proton number </li></ul>59 -7 35 bromine 184 114 53 iodine - - 85 astatine 17 9 Proton Number -101 -220 Melting Point (°C) -35 chlorine -188 fluorine Element Boiling Point (°C)
  11. 11. outer shell electrons metals are arranged in order of Periodic Table proton number group period non-metals a vertical set of elements is a are on the right side of horizontal row is a are on the left side of increases down a group number have many is the same as the number of have the same number of have few from left to right across a change from metals to non-metals

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