Question
Among the elements B, Al, C and Si:
  1. Which element has the highest first ionisation enthalpy?
  2. Which element has the most metallic character? Justify your answer in each case.

Answer

Arranging the elements into different groups and periods:
Group
13
14
Period 2
B
C
Period 3
Al
Si
  • Ionization enthalpy increases along a period and decreases down a group. Therefore, C has the highest first ionization enthalpy.
  • Metallic character decreases along a period and increases down a group. Therefore, Al has the most metallic character.

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