Chemistry 2

Periodic Properties and the Structure of the Table

  1. Elements in the same group (or column) have the same chemical properties.
    1. All the elements in a group (or column) are called families.
    2. Group 8: The Noble Gases, don't react with other elements.
    3. Group 1: The Alkali Earth Metals, all react with water in the following manner
      2 Li + H2O ---> H2 + 2 LiOH
      2 Na + H2O ---> H2 + 2 NaOH
      ...
      2 Fr + H2O ---> H2 + 2 FrOH
      Using the Periodic Table to Predict Formulas
      Known Formula: Predicted formula:
      B2O3 Aluminum + Oxygen =
      H2O Hydrogen + Sulfur =
      SiO2 Carbon + Oxygen =
      HF Hydrogen + Chlorine =
      Ba(OH)2 Magnesium + Hydroxide =
  2. Periodic Properties
    1. As you move across a row various properties change regularly click on the images below to see a visualization of the various properties. All of these images are from www.webelements.com, one of the best periodic table sites on the web.
      Periodic Trends

      Summary of Trends
  3. Early on the elements were divided into two broad categories -> metals and non-metals. This was done long before anyone knew any detail about the atoms or any of the periodic properties mentioned above.
  4. As you can see what makes something a metal or a non-metal is based on other properties like ionization energy, atomic radius, and electronegativity
  5. When metal atoms are bonded together the electrons become delocalized, jumping from one atom to another. A common analogy is to say that the nuclei of atoms in a metal exist in a "sea of mobile electrons".
  6. This is due to the low ionization energy of these electrons, and is what gives metals the property of conductivity. A typical electric current can be described as electrons moving from one place to another. This can easily happen in metallic substances as depicted below.
  7. Why does it make sense that atoms on the lower left of the table have the most metallic character and those on the upper right have the most non-metalic character. Look at the properties and how the trends change as you go across or down the table.