Classification of Elements

Specification Point 6.1:
  • Explain why some elements can be classified as alkali metals (group 1), halogens (group 7) or noble gases (group 0), based on their position in the periodic table.
  • Elements are arranged on the Periodic table in order of increasing atomic number where each element has one proton more than the element preceding it.
  • The table is arranged in vertical columns called Groups numbered I – VIII and in rows called Periods.
  • The Period number tells you the number of electron shells an atom has: 
    • E.g. elements in Period 3 have 3 electron shells.
  • The Group number tells you how many outer electrons each atom has:
    • E.g. Group 6 elements have atoms with 6 electrons in the outermost shell.
  • The Periodic Table positions elements based on their properties which are linked to their electronic configurations.
  • Elements with the same number of electrons in the outer shell and hence similar chemical properties are placed in the same Group.
  • This allows us to use the table to predict the properties of elements based on their position.
  • Groups 1, 7 and 0 are elements which have been classified into their respective groups using the Periodic Table.

PT Groups and Periods, Edexcel GCSE Chemistry

The Periodic Table arranges the elements in Groups and Periods 

Edexcel GCSE Chemistry Notes

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Morgan Curtin Chemistry

Author: Morgan

Morgan’s passion for the Periodic Table begun on his 10th birthday when he received his first Chemistry set. After studying the subject at university he went on to become a fully fledged Chemistry teacher, and now works in an international school in Madrid! In his spare time he helps create our fantastic resources to help you ace your exams.