AP Music Theory Unit 7 Cheatsheet: Harmony and Voice Leading IV - Secondary Function

Tonicization = making a non-tonic chord sound temporarily like a tonic, without changing the primary key.

• Fleeting, brief harmonic event
• No clear cadence in the new key
• Primary key remains unchanged
• Achieved by altering diatonic scale degrees (shown with accidentals)

Key distinction: Tonicization ≠ modulation. A tonicized chord feels like a temporary tonic; the actual tonic never changes.

Definition: Diminished triads or diminished seventh chords whose root is the leading tone of the chord being tonicized.

Function: Tonicize any major or minor triad, just like secondary dominants.

Inversion rules:

• Triads: first inversion only (vii°⁶)
• Seventh chords: any inversion appropriate to context

Half-diminished leading-tone seventh chords (viiø⁷) tonicize major chords; leading-tone seventh chords tonicizing minor chords are fully diminished (vii°⁷).

Therefore, secondary leading-tone chords that are half-diminished may only tonicize major triads.

Example: In C major, viiø⁷/IV (E–G–B♭–D) tonicizes F major. In C minor, the secondary leading-tone chord of iv is vii°⁷/iv (E–G–B♭–D♭).