The Periodic Table

The Periodic Table

Basic Concepts

  • The Periodic Table is a tool to organise and display the elements based on their chemical properties.
  • The elements in the Periodic Table are arranged in order of increasing atomic number (which is equal to the number of protons in an atom).
  • Each box on the table contains the chemical symbol, atomic number, and relative atomic mass of an element.
  • A ‘Period’ is a horizontal row and a ‘Group’ is a vertical column on the Periodic Table.


  • Elements in the same group have the same number of electrons in their outer energy level.
  • The group number corresponds to the number of valence electrons.
  • Elements in the same group often share similar chemical properties due to the number and arrangement of their valence electrons.


  • Elements are placed in different periods (rows) based on the number of electron shells they have.
  • The period number equals the total number of electron shells that are occupied in an atom of that element.

Types of Elements

  • The Periodic Table divides elements into Metals, Non-metals, and Metalloids (Semiconductors).
  • Metals are good conductors of heat and electricity, are ductile, malleable, and have high melting points.
  • Non-metals are poor conductors of heat and electricity and are not ductile or malleable.
  • Metalloids have properties intermediate between those of metals and non-metals.

Transition Metals and Inner Transition Metals

  • Transition metals are elements in groups 3 to 12 with d orbitals being filled.
  • They have properties different from other metals (e.g., they can have multiple oxidation states, and form coloured compounds).
  • Inner transition metals are in the two rows at the bottom of the Periodic Table, known as the Lanthanide and Actinide series, with f orbitals being filled.

Noble Gases

  • The Noble gases, Group 18, are all unreactive elements, due to having a full outer shell of electrons.
  • This makes them very stable and not prone to form bonds with other atoms.

Remember, a solid understanding of the Periodic Table will aid in grasping more complex chemical reactions and interactions!