PeriodsOfElements

• There are seven periods numbered from 1 to 7.
  • The number of the period an element is in, in general, is the same number of the energy level of the elements valence electrons.
• Periods 1,2,and 3 are known as short periods.
  • Atoms of these elements have only s and p electrons
• Periods 4 and 5 are long
  • Contain Transition Elements which is any element with an atom (or a cation) that has an incomplete d subshell
• Periods 6 and 7 contain series of transition elements called lanthanoids and actinoids respectively
  • Both of these are characterized as filling the f sublevel

[Another Periodic Table]