Heteronuclear Diatomics and Polarity in Orbital Terms · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Unequal atoms share unequally

Science · Chemistry · ages 18-19
Name ______________________   Date ____________

  1. What two conditions must orbitals meet to interact usefully?

    • Close energies plus matching symmetry
    • Large size plus many electrons
    • Equal mass plus equal charge

  2. Which atom dominates the bonding orbital in a heteronuclear pair?

    • The higher energy atom
    • Both atoms exactly equally
    • The lower energy, more electronegative atom

  3. The antibonding combination takes after the higher energy partner.

    Circle one:   True   False

  4. Two atoms with a huge energy mismatch bond. What character results?

    • More evenly shared
    • Unchanged in character
    • More one sided, toward ionic

  5. In hydrogen fluoride, which atom do the bonding electrons sit closer to?

    • Hydrogen, the lighter atom
    • Fluorine, the more electronegative atom
    • Both atoms exactly equally

  6. Carbon monoxide binds to metals. Through which atom, and why?

    • Through carbon, using its carbon centred lone pair
    • Through oxygen, using its lower orbitals
    • Through both atoms at once

  7. Carbon dioxide has polar bonds yet no permanent dipole. Why?

    • Its bond dipoles cancel by symmetry
    • Its bonds are perfectly equal
    • Carbon dioxide has no polar bonds

  8. A student combines two orbitals with close energies but different symmetry. What is the error?

    • Energies matched, so symmetry is optional
    • Symmetry mismatched means no combination
    • Overlap cares only about distance
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Unequal atoms share unequally W1-mt_thdxFqyHJV-s1

  1. Close energies plus matching symmetry · Pairs failing either test stay nearly nonbonding.
  2. The lower energy, more electronegative atom · Bonding combinations take after the lower partner.
  3. True · Each combination takes after one parent: bonding the lower, antibonding the higher.
  4. More one sided, toward ionic · Big gaps localise the electrons on one partner.
  5. Fluorine, the more electronegative atom · Piled up bonding electrons are the dipole made visible.
  6. Through carbon, using its carbon centred lone pair · The donating orbital lives mostly on carbon.
  7. Its bond dipoles cancel by symmetry · Geometry adds dipoles as vectors, and symmetry can zero them.
  8. Symmetry mismatched means no combination · Both tests must pass, or the pair stays nonbonding.
Worksheet · LightMySky