The Periodic Table

• Periodic Table


  An essential tool in chemistry, organizing elements based on their properties and atomic structure
• Arrangement of Elements


  1. In order of atomic number

  2. In groups and periods
• Atomic number


  Number of protons in the nucleus
• Arrangement of elements by atomic number

  • Hydrogen (H) has atomic number 1
  • Helium (He) has atomic number 2
  • Lithium (Li) has atomic number 3
• Groups


  Vertical columns in the Periodic Table, elements in same group have similar chemical properties
• Periods


  Horizontal rows in the Periodic Table, properties of elements change progressively across a period
• Electronic configuration


  Distribution of electrons in atomic orbitals
• Deducing electronic configurations of first 20 elements


  1. From group number (number of electrons in outermost shell)

  2. From period number (number of occupied electron shells)
• Electronic configurations


  • Hydrogen (H): 1 (1 electron in 1st shell)
  • Carbon (C): 2, 4 (2 electrons in 1st shell, 4 in 2nd shell)
  • Calcium (Ca): 2, 8, 8, 2 (2 electrons in 1st shell, 8 in 2nd shell, 8 in 3rd shell, 2 in 4th shell)
• Metals


  Conduct electricity well due to presence of free-moving electrons
• Non-metals


  Generally do not conduct electricity well
• Metal oxides


  Usually basic (e.g. sodium oxide reacts with water to form a base, sodium hydroxide)
• Non-metal oxides


  Usually acidic (e.g. carbon dioxide reacts with water to form an acid, carbonic acid)
• Metals


  • Found on the left and in the center of the Periodic Table
• Non-metals


  • Found on the right side of the Periodic Table
• Main group elements


  Position determined by electronic configuration: group number corresponds to number of electrons in outer shell, period number corresponds to number of occupied electron shells
• Sodium (Na)


  • 2, 8, 1 (Group 1, Period 3)
• Similarity of elements in same group

  Have similar chemical properties because they have same number of electrons in outer shell
• Group 1 elements (alkali metals)


  • Lithium, sodium, potassium all react vigorously with water
• Noble gases (Group 0)

  Very stable and do not readily react because they have full outer electron shells
• Noble gases


  • Helium (He), neon (Ne), argon (Ar)