Curly Arrows as the Language of Mechanism · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Arrows that say where electrons go

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

  1. What does a single headed fishhook arrow move?

    • A full positive charge
    • A pair of electrons
    • A single electron in a radical step

  2. Where must the tail of a curly arrow sit?

    • At any atom with a formal charge
    • At a lone pair or a bond
    • At the product side of the step

  3. A curly arrow shows an atom migrating from one place to another.

    Circle one:   True   False

  4. An arrow lands a fifth bond on carbon. What is your verdict?

    • It is fine for very reactive intermediates
    • It is allowed when the carbon is charged
    • It is illegal, since carbon cannot hold five bonds

  5. You assign formal charges before and after a step. What must hold?

    • The totals must match on both sides
    • The products must show zero charges
    • Charges are ignored during mechanisms

  6. Where must the head of a curly arrow point?

    • At the atom the electrons came from
    • Where the electron pair arrives
    • At the slowest step of the sequence

  7. A step starts neutral but its products sum to minus one. Can it stand?

    • Yes, charges vanish whenever bonds rearrange
    • Yes, if the missing charge hides on hydrogen
    • No, the totals must balance, so one arrow is wrong

  8. A step is drawn with three arrows, one of them faulty. Which one is it?

    • The arrow that overloads an atom past its octet
    • The arrow with the longest shaft
    • The arrow drawn closest to the solvent
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Answer key

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

Arrows that say where electrons go W1-mt_C0bq2Mu8HT-s1

  1. A single electron in a radical step · Fishhooks are reserved for one electron radical moves.
  2. At a lone pair or a bond · Tails mark electron sources, and only pairs or bonds qualify.
  3. False · Arrows move electron pairs or single electrons, never atoms.
  4. It is illegal, since carbon cannot hold five bonds · The octet caps carbon at four bonds, so redraw that arrow.
  5. The totals must match on both sides · Charge is bookkeeping: what goes in must come out.
  6. Where the electron pair arrives · Heads mark destinations: the new bond or lone pair.
  7. No, the totals must balance, so one arrow is wrong · Unbalanced charge always means a faulty arrow somewhere.
  8. The arrow that overloads an atom past its octet · Grammar beats looks: an overloaded atom convicts its arrow.
Worksheet · LightMySky