CIE IGCSE Chemistry

Revision Notes

9.1.2 Periodic Trends

The Metallic Character of Elements

  • The metallic character of the elements decreases as you move across a Period on the Periodic table, from left to right, and it increases as you move down a Group
  • This trend occurs due to atoms more readily accepting electrons to fill their valence shells rather than losing them to have the below, already full, electron shell as their outer shell
  • Metals occur on the left-hand side of the Periodic table and nonmetals on the right-hand side
  • Between the metals and the nonmetals lie the elements which display some properties of both
  • These elements are referred to as metalloids or semi-metals

Properties of metals and nonmetals
Properties of metals and nonmetals table, IGCSE & GCSE Chemistry revision notes


Metals, non-metals & metalloids in Periodic Table, IGCSE & GCSE Chemistry revision notesA zig-zag line in this diagram separates the metals on the left, from the nonmetals on the right

Extended Only

Element Trends & Electronic Configurations

Electronic configuration and the Periodic table

  • The electronic configuration is the arrangement of electrons into shells for an atom (e.g: the electronic configuration of carbon is  2, 4)
  • There is a link between the electronic configuration of the elements and their position on the Periodic table
  • The number of notations in the electronic configuration will show the number of shells of electrons the atom has, showing the Period
  • The last notation shows the number of outer electrons the atom has, showing the Group number

Example:  Electronic configuration of Chlorine:

Chlorine Electronic configuration, IGCSE & GCSE Chemistry revision notesThe electronic configuration of chlorine as it should be written


Period: The red numbers at the bottom show the number of notations which is 3, showing that a chlorine atom has 3 shells of electrons.

Group: The green box highlights the last notation which is 7, showing that a chlorine atom has 7 outer electrons.


Chlorine in Periodic Table, IGCSE & GCSE Chemistry revision notesThe position of chlorine on the Periodic table


Chemical properties of elements in the same group

  • Elements in the same Group in the Periodic table have similar chemical properties
  • When atoms collide and react, it is the outermost electrons that interact
  • The similarity in their chemical properties stems from having the same number of electrons in their outer shell
  • For example, both lithium and sodium are in Group 1 and can react with elements in Group 7 to form an ionic compound (charges of Group 1 ions are +1, charges of Group 7 ions are -1)

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.

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