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Electronegativity and bond polarityEdexcel International A Level Chemistry: Flashcards

What these 12 flashcards ask

  • Define electronegativity.
  • What is a polar bond?
  • What do δ+ and δ− mean?
  • Which atom is δ− in a polar bond?
  • What makes a bond more polar?
  • When is a covalent bond non-polar?
  • How are ionic and covalent bonding related?
  • What happens if the electronegativity difference is very large?
  • Why is CO₂ non-polar although C=O bonds are polar?
  • Why is water polar?
  • Why is CCl₄ non-polar but CHCl₃ polar?
  • What is needed for a molecule to be polar?

Exam questions on Electronegativity and bond polarity

  1. Pauling electronegativity values: H 2.20, C 2.55, Cl 3.16, F 3.98 and Na 0.93.
    Explain, using the data, why sodium chloride is ionic whereas hydrogen chloride is polar covalent.2 marks
  2. Pauling electronegativity values: H 2.20, C 2.55, O 3.44 and Cl 3.16. Carbon dioxide is a linear molecule (O=C=O), water is a bent (V-shaped) molecule, and chloromethane, CH₃Cl, methane, CH₄, and tetrachloromethane, CCl₄, are all tetrahedral.
    Explain why water is a polar molecule.2 marks
  3. Pauling electronegativity values: H 2.20, F 3.98, Cl 3.16, I 2.66, Na 0.93 and Si 1.90.
    Calculate the electronegativity difference in H–F, H–Cl and H–I. State which bond is the most polar and the direction of the dipole in that bond.3 marks
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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).