Unit Big Picture
This unit introduces the concept of tonicization, the first major step beyond diatonic harmony. By using secondary function chords, we can make a non-tonic chord sound like a temporary tonic, adding color, tension, and sophistication. This process expands our harmonic vocabulary with chromaticism, creating stronger forward motion and enabling more complex musical phrases. Mastering secondary function is crucial for understanding how composers create harmonic interest and prolong musical ideas within a single key.
Core Threads
Thread 1: Functional Harmony & Cadences
Expanding Dominant Function: We learn that the powerful V–I relationship can be applied to chords other than the tonic. A secondary dominant, such as V/V, creates a strong pull to the dominant chord, making its arrival more impactful.
Alternative Dominant Colors: Secondary leading-tone chords (e.g., vii°/V) serve a similar dominant function to their secondary dominant counterparts. They provide a different chromatic flavor while still intensifying the arrival of the tonicized chord.
Thread 2: Voice-Leading & Texture
Managing Chromaticism: The introduction of secondary chords requires careful handling of new chromatic pitches. The most important rule is resolving the temporary leading tone (the chromatically raised note) up by half step to the root of the tonicized chord.
Resolving Dissonance: When part writing secondary dominant seventh chords (e.g., V7/V), both the temporary leading tone and the chordal seventh must resolve correctly, creating smooth, coherent four-part textures.
Concept Progression
| Step | Concept | Builds On | Why It Matters |
|---|---|---|---|
| 1 | Diatonic Dominant Function | The V–I relationship | Establishes the foundational pattern of tension and resolution. |
| 2 | Tonicization with V/x | V–I relationship | Applies the dominant function to non-tonic chords, creating temporary tonal centers. |
| 3 | Analysis of V/x | Roman numeral analysis | Provides the notational system (e.g., V/V, V7/ii) to label these new chords. |
| 4 | Tonicization with vii°/x | vii°–i relationship | Extends the concept of tonicization to a different type of dominant-functioning chord. |
Turning Points
| New Tool Introduced | What It Enables | Why It Mattered |
|---|---|---|
| The Secondary Chord | Tonicizing any major or minor diatonic triad within a key. | It is the primary engine of chromatic harmony, adding depth without fully modulating. |
| The Temporary Leading Tone | Creating a strong, localized pull toward a diatonic chord. | It is the key ingredient that gives a secondary chord its dominant function and distinct sound. |
Unit Evidence Bank
Secondary Dominant: A dominant chord (V or V7) that is not the primary dominant of the key but instead resolves to another diatonic chord. It is labeled with a slash, e.g., V/V.
Tonicization: The process of making a non-tonic chord sound like a temporary tonic by preceding it with its own dominant or leading-tone chord.
V/V ("five of five"): The dominant of the dominant. In C major, V/V is a D major chord (the dominant of G major) that resolves to the V chord (G major).
Secondary Leading-Tone Chord: A leading-tone chord (vii° or viiø7) that resolves to a diatonic chord other than the tonic. It is labeled vii°/V, vii°7/ii, etc.
Chromaticism: The use of pitches foreign to the established key signature. Secondary chords are the most common source of functional chromaticism.
Temporary Leading Tone: The chromatically altered pitch within a secondary chord that functions as the leading tone to the root of the chord being tonicized (e.g., F♯ in a V/V in C major).
Analytical Notation (Slash Chords): The Roman numeral notation "X/Y" is read as "X of Y." It denotes a chord with a function (X) applied to a temporary tonic (Y).
Non-Tonicizable Chords: Diminished triads (like vii° in major or ii° in minor) are generally not tonicized with secondary dominants because they cannot function as stable temporary tonics.
Topic Navigator
| Topic Title | What This Adds (≤10 words) |
|---|---|
| 7.1: Tonicization through Secondary Dominant Chords | Using V/x chords to create temporary tonal centers. |
| 7.2: Part Writing of Secondary Dominant Chords | Voice-leading rules for chromatic notes in V/x chords. |
| 7.3: Tonicization through Secondary Leading Tone Chords | Using vii°/x chords as an alternative to V/x. |
| 7.4: Part Writing of Secondary Leading Tone Chords | Voice-leading rules for chromatic notes in vii°/x chords. |
Exam Skills Focus
Functional: A chromatic chord (V/x) intensifies the arrival of its diatonic resolution chord.
Voice-Leading: The temporary leading tone (the new sharp or natural) resolves up by half step.
Aural: An unexpected chromatic pitch often signals the presence of a secondary dominant.
Common Misconceptions & Clarifications
Misconception: A secondary dominant always creates a key change. → Clarification: It creates temporary tonicization, not a full modulation. The music quickly returns to the home key.
Misconception: The chord V/IV must be a minor chord because IV is the subdominant. → Clarification: The quality of a secondary dominant is based on the key of the chord it tonicizes. Since IV is a major chord, its dominant (V/IV) is also a major chord (I in C major).
Misconception: Any chord with an accidental is a secondary dominant. → Clarification: The chord must function as a dominant to the chord that follows it. A chromatic pitch can also be part of other chords or simply be a non-chord tone.
Summary
This unit moves beyond basic diatonic harmony by introducing secondary function, a powerful tool for creating musical interest through tonicization. By learning to identify, analyze, and write secondary dominant (V/x) and secondary leading-tone (vii°/x) chords, you gain access to the world of functional chromaticism. These chords intensify the arrival of diatonic harmonies by temporarily treating them as tonic. Mastering the voice-leading of these new chromatic pitches, especially the upward resolution of the temporary leading tone, is essential for creating smooth and logical harmonic progressions. This skill set is fundamental to analyzing and composing more complex and expressive music.