Chemistry Practice Problems Periodic Trends: Atomic Radius Practice Problems Solution: Arrange these elements in order of decreasing radi...

Solution: Arrange these elements in order of decreasing radius: S, Ca, F, Rb, and Si.

Problem

Arrange these elements in order of decreasing radius: S, Ca, F, Rb, and Si.

Solution
  • For a diatomic molecule, atomic radius is defined as half the distance between the nuclei in a molecule of two identical elements
  • In general, atomic radius decreases from left to right across a period. Reason is as protons (atomic number) are added in a period, electrons also increases in the same principal energy level. 
  • More protons will cause more positive charge which attract electrons closer to the nucleus.


  • Another trend is that atomic radius decreases from bottom to top. Reason is that as it goes down a group, new valence shell is added. 
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