CIE A Level Chemistry复习笔记1.3.2 Electronegativity Trends

Electronegativity: Trends

  • Electronegativity varies across Periods and down the Groups of the Periodic Table

Down a group

  • There is a decrease in electronegativity going down the Group
  • The nuclear charge increases as more protons are being added to the nucleus
  • However, each element has an extra filled electron shell, which increases shielding
  • The addition of the extra shells increases the distance between the nucleus and the outer electrons resulting in larger atomic radii
  • Overall, there is decrease in attraction between the nucleus and outer bonding electrons

1.3-Chemical-Bonding-Trends-Down-a-Group

Electronegativity decreases going down the groups of the periodic table

Across a period

  • Electronegativity increases across a Period
  • The nuclear charge increases with the addition of protons to the nucleus
  • Shielding remains reasonably the same across the Period as no new shells are being added to the atoms
  • The nucleus has an increasingly strong attraction for the bonding pair of electrons of atoms across the Period of the Periodic Table
  • This results in smaller atomic radii

1.3-Chemical-Bonding-Trends-Across-a-Group

Electronegativity increases going across the periods of the Periodic Table

Trends down a group & across a period table

1.3-Chemical-Bonding-Table_3

Exam Tip

Remember the general trend is an increase in electronegativity towards the top right of the Periodic Table.Fluorine is the most electronegative element in the periodic table.

 

 

 

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