Electronegativity | Covalent Bonding and Molecular Structure

General Chemistry 1 - Electronegativity

  1. 1) Which of the following compounds would be the most ionic?
    Al2O3, Na2S, MgCl2, CsF

     
  2.  Which of the following compounds has the least ionic character?
    CaCl2, AlCl3, CCl4, KCl

To answer this question, you need to study the difference in electronegativity between atoms

  1. Electronegativity: Al = 1.5; O = 3.5; Na = 0.9; S = 2.5; Mg = 1.2; Cl = 3.0; Cs = 0.7; F = 4.0 
    ⇒ CsF is the most ionic compound (greater difference in electronegativity)
    In addition, Cs is the lowest element on the left of the periodic table while F is the highest element on the right ⇒ without knowing the electronegativity values of the elements, we can easily conclude that CsF is the most ionic compound
     
  2.  Electronegativity: Ca = 1.0; Cl = 3.0; Al = 1.5; C = 2.5; K = 0.8
    ⇒ CCl4 has the least ionic character (lower difference in electronegativity)