Electronegativity order of group 13

General
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electronegativity order of group 13

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Electronegativity Order of Group 13 Elements

Answer:

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. Within a group in the periodic table, electronegativity tends to decrease as you move down the group, as the additional electron shells increase the atomic radius and reduce the effective nuclear charge experienced by the outermost electrons.

In Group 13 of the periodic table, the elements include:

  1. Boron (B)
  2. Aluminum (Al)
  3. Gallium (Ga)
  4. Indium (In)
  5. Thallium (Tl)

Electronegativity Order:

For Group 13, the electronegativity generally decreases from Boron to Thallium. The electronegativity order can be approximately represented as follows:

  • Boron (B): Boron has the highest electronegativity in Group 13.
  • Gallium (Ga): Due to its d-block contraction, Gallium’s electronegativity is slightly higher than Aluminum.
  • Aluminum (Al): Lower than Boron and similar to other larger elements.
  • Indium (In): Decreases further as compared to Aluminum and Gallium.
  • Thallium (Tl): The lowest electronegativity in Group 13, being the heaviest atom in the group.

Detailed Electronegativity Values:

  • Boron (B): 2.04
  • Gallium (Ga): 1.81
  • Aluminum (Al): 1.61
  • Indium (In): 1.78
  • Thallium (Tl): 1.62

Explanation of Trends:

  • Boron: Being the smallest element in this group, it has the highest electronegativity, as the nucleus can attract its valence electrons more effectively due to lesser shielding of inner electrons.

  • Gallium vs. Aluminum: The unexpected increase in electronegativity from Aluminum to Gallium is a result of the d-block contraction. Gallium’s electrons are held tighter than Aluminum’s because the d-electron cloud is compact and causes greater effective nuclear charge.

  • Indium and Thallium: Further down the group, a steady decrease in electronegativity is observed. This is due to the increased atomic size and increased shielding, reducing the effective nuclear charge that is experienced by the valence electrons.

Final Answer:

The electronegativity order of group 13 elements from highest to lowest is:

  • Boron (B) > Gallium (Ga) > Indium (In) ≈ Thallium (Tl) > Aluminum (Al)

This order reflects the larger atomic sizes and the associated decrease in effective nuclear charge as we move down the group, with the noted exception due to the d-block contraction affecting Gallium’s position.