Among the following elements, the one with the lowest electronegativity is :

Correct option is B

The correct answer is (b) Cs.

Electronegativity is the tendency of an atom to attract shared electrons in a chemical bond.

Trends in Electronegativity:

1. Down a group: Electronegativity decreases because the atomic size increases, and valence electrons are farther from the nucleus.
2. Across a period: Electronegativity increases due to increasing nuclear charge and smaller atomic size.

Comparison of Elements:

• Lithium (Li):

  • Electronegativity: ~1.0
  • Group 1, Period 2.
  • More electronegative than cesium but less than nitrogen or chlorine.

• Cesium (Cs):

  • Electronegativity: ~0.7
  • Group 1, Period 6.
  • Lowest electronegativity among the given options due to its large atomic size and weak attraction to electrons.

• Chlorine (Cl):

  • Electronegativity: ~3.0
  • Group 17, Period 3.
  • A highly electronegative element as it belongs to the halogens.

• Nitrogen (N):

  • Electronegativity: ~3.0
  • Group 15, Period 2.
  • One of the most electronegative elements due to its small size and strong attraction to electrons.

Additional Information:

• Cesium (Cs) has the lowest electronegativity because it belongs to Group 1 (alkali metals) and is located at the bottom of the group.
• Its large atomic size and low effective nuclear charge result in weak electron-attracting power.