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Periodic Trends

Jamie Z 2024-06-07

Learning Goals

  • Explain trends in atomic radii and ionic radii for groups and periods

Atomic Radius

  • Half the distance between the nuclei in a molecule consisting of two identical atoms

Group Trend

The atomic radius increases down a group as there is higher electron shielding due to more energy levels (shells). The distance between valence electrons from nucleus down a group.

Period Trend

Across a period the electron shielding stays the same because the number of shells doesn’t change. However the number of protons increases so the electrostatic attraction increases and the electrons are pulled closer to the nucleus.

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Ionic Radius

  • The distance measured from the centre to neighbouring ions
  • The periodic trends is the same as atoms
  • Metals will get smaller and Non metals will get bigger