Specification Point 1.18:
Understand how elements are arranged in the periodic table: in order of atomic number, in groups and periods

Understanding the Periodic Table

All elements are arranged in the periodic table


  • Horizontal rows that show the number of shells of electrons an atom has


  • Vertical columns that show how many outer electrons an atom has
  • E.g Group 3 elements have atoms with 3 electrons in the outermost shell
  • Group 0 have 8 electrons in the outermost shell.

The Periodic Table:

The Periodic Table, Edexcel IGCSE Chemistry

All elements are arranged in the order of increasing atomic number from left to right

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Author: Jamie

Jamie got a First class degree in Chemistry from Oxford University before going on to teach chemistry full time as a professional tutor. He’s put together these handy revision notes to match the Edexcel IGCSE Chemistry specification so you can learn exactly what you need to know for your exams.