classification of elements


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classification of elements

  1. 1. Classification of Elements January 13, 2011
  2. 2. Objectives <ul><li>Describe characteristics of metals, nonmetals, and metalloids </li></ul><ul><li>Define period, periodic law, family, malleable, ductile. valence electrons </li></ul><ul><li>Describe how elements are arranged on the periodic table </li></ul>
  3. 4. Henry Mosley (1914) <ul><li>Determined that each atom has a unique number of positive charges. </li></ul><ul><li>Discovered isotopes </li></ul><ul><li>Rearranged Mendeleyev’s table by their atomic number </li></ul>
  4. 6. Periodic Law <ul><li>Because properties of elements repeated in an orderly way, it was called periodic . </li></ul><ul><li>Properties of elements are a function of their atomic numbers.  </li></ul>
  5. 7. Elements are arranged: Vertically into Groups or Families Horizontally Into Periods
  6. 8. Valence Electrons <ul><ul><li>Number of electrons an element has in its outermost orbital </li></ul></ul><ul><ul><li>Families have the same number of valence electrons </li></ul></ul><ul><ul><li>Group number tells how many valence electrons each family will have </li></ul></ul>
  7. 9. The group 2 atoms all have 2 electrons in their outer shells Be (Beryllium) Atom Mg (Magnesium) Atom
  8. 10. If you looked at an atom from each element in a period Each atom has the same number of electron shells .
  9. 11. The period 4 atoms each have 4 electron containing shells K (Potassium) Atom Fe (Iron) Atom Kr (Krypton) Atom 4 th Shell
  10. 12. Metals <ul><li>shiny (they have luster) </li></ul><ul><li>solids at room temperature </li></ul><ul><li>good conductors </li></ul><ul><li>malleable - capable of being hammered out into thin sheets </li></ul><ul><li>ductile - drawn out into wire or threads </li></ul>
  11. 13. <ul><li>Located to the left of the zigzag line </li></ul><ul><li>Most elements are metals </li></ul><ul><li>Usually have few valence electrons </li></ul>
  12. 14. Non-metals <ul><li>Can be found as solids, liquids, or gases at room temperature </li></ul><ul><li>Typically dull and brittle </li></ul><ul><li>Poor conductors </li></ul><ul><li>All non-metals except hydrogen are found on the right side of the zigzag line </li></ul><ul><li>Many valance electrons </li></ul>
  13. 15. Metalloids <ul><li>Border both sides of the zigzag line </li></ul><ul><li>each has some of the properties of a metal and non metal </li></ul><ul><li>can become good conductors under certain conditions such as high temperatures </li></ul><ul><li>Also called semiconductors </li></ul>