Secondary dominants are chords that briefly make a chord other than the tonic sound like a temporary goal. This cheat sheet helps students recognize, label, spell, and resolve applied dominant chords in tonal music. It is especially useful for Roman numeral analysis, part writing, harmonic dictation, and composition.
Students need these patterns because they explain many chromatic notes that do not belong to the main key.
Key Facts
- A secondary dominant is labeled V/x or V7/x, where x is the temporary tonicized chord within the home key.
- To build V/x, find the root of chord x, then build a major triad a perfect fifth above it.
- To build V7/x, build a dominant seventh chord a perfect fifth above x, using root, major third, perfect fifth, and minor seventh.
- In major keys, common secondary dominants include V/V, V/ii, V/iii, V/IV, and V/vi.
- In minor keys, common secondary dominants include V/V, V/iv, V/VII, V/III, and V/VI, depending on the harmonic context.
- The leading tone of the tonicized chord is usually raised with an accidental and should resolve upward by half step to the temporary tonic.
- A secondary dominant normally resolves to its target chord, so V/V resolves to V and V7/ii resolves to ii.
- A secondary dominant tonicizes a chord briefly, but it does not create a full modulation unless the new key is confirmed for a longer passage.
Vocabulary
- Secondary dominant
- A dominant-function chord that temporarily points to a diatonic chord other than the main tonic.
- Tonicization
- The brief emphasis of a chord as if it were a temporary tonic without fully changing keys.
- Applied chord
- A chord borrowed from the key of a temporary tonic and used to strengthen the arrival on that chord.
- V/x
- A Roman numeral label meaning the dominant chord of the chord shown after the slash.
- Leading tone
- A note one half step below a tonic or temporary tonic that has a strong tendency to resolve upward.
- Modulation
- A longer change of key that is confirmed by cadences or sustained harmonic activity in the new key.
Common Mistakes to Avoid
- Labeling every accidental as a secondary dominant is wrong because chromatic notes can also come from mixture, passing tones, neighbor tones, or modulation.
- Building V/x on chord x is wrong because the dominant of x is built a perfect fifth above x, not on x itself.
- Forgetting to raise the leading tone is wrong because a secondary dominant usually needs a major third that pulls strongly toward the temporary tonic.
- Calling a brief tonicization a modulation is wrong because modulation requires a more stable change of key, often supported by a cadence in the new key.
- Resolving V7/x to the wrong target chord is wrong because the slash chord tells the resolution goal, so V7/vi should resolve to vi.
Practice Questions
- 1 In C major, spell the notes of V/V and name the chord it should resolve to.
- 2 In G major, spell the notes of V7/ii and name the chord it should resolve to.
- 3 In F major, identify the Roman numeral for the chord A major when it resolves to D minor.
- 4 Explain why the progression C major, A7, D minor, G7, C major is tonicization rather than a full modulation to D minor.