Classification (Oxford AQA International A Level Chemistry)

The Periodic Table: Structure & Classification

• The Periodic Table is a list of all known elements arranged in order of increasing atomic number (proton number)

• Elements are arranged in rows called periods

  • Atoms with the same number of shells are in the same period

• Elements are arranged in columns called groups

  • Atoms with similar electronic configurations in the outer shell are placed in groups

The Periodic Table

• All elements belong to one of four main blocks:

  • s-block

  • p-block

  • d-block

  • f-block

• The block an element is in indicates which sub-shell its outer electron is found in

  • E.g. Magnesium has the electronic configuration 1s²2s²2p⁶3s³ o is located in p- block

The blocks in the Periodic Table

• Elements in the same group show similar chemical properties

• As atomic number increases, the properties of the elements show trends which repeat themselves in each period of the periodic table

  • These trends are known as periodic trends and the study of these trends in known as periodicity