Getting Started
Having mastered diatonic chords and their functions within a key, we now explore how composers add color and interest by temporarily emphasizing chords other than the tonic. This process introduces chromaticism—the use of notes outside the established key—to create more dynamic and compelling harmonic progressions. This is a fundamental technique for creating harmonic tension and release on a local level.
What You Should Be Able to Do
Identify secondary dominant chords in a musical score by locating their characteristic accidentals and harmonic context.
Provide a correct Roman numeral analysis for a secondary dominant chord and its resolution to a temporary tonic.
Describe the process of tonicization in a given musical excerpt, explaining how a non-tonic chord is made to sound temporarily stable.
Aurally distinguish the sound of a secondary dominant resolving to its temporary tonic within a harmonic progression.
Spell a secondary dominant chord in any given key, correctly applying the necessary accidentals.
Key Concepts & Analysis
The strongest harmonic relationship in tonal music is that of the dominant resolving to the tonic (V–I). This motion provides a powerful sense of arrival and closure. Tonicization borrows this power and applies it, on a temporary basis, to other chords in the key.
A tonicization is the process of making a non-tonic scale degree or chord sound like a temporary tonic. This is a fleeting harmonic event that does not change the primary key of the music. It is achieved by preceding a diatonic chord with its own dominant, making that diatonic chord sound, for a moment, like a point of arrival.
The chord that accomplishes this is called a secondary dominant. A secondary dominant is the dominant (V) or dominant seventh (V⁷) chord of a diatonic chord other than the tonic. We use a special notation for this: V/X or V⁷/X, read as "five of X" or "five-seven of X," where X is the Roman numeral of the chord being tonicized. For example, V⁷/V is the dominant seventh chord of the dominant.
To build a secondary dominant, one must use notes from the key of the chord being tonicized. This nearly always requires altered scale degrees—notes raised or lowered chromatically from the home key, which appear as accidentals in the score. For example, in C major, the dominant chord is G major (G–B–D). The dominant of G major is D major (D–F♯–A). The F♯ is an accidental in the key of C major; it is the temporary leading tone to G.
Functions & Allowable Motions
The function of a secondary dominant is always dominant, but its pull is directed toward a temporary tonic rather than the primary tonic of the key. This creates a localized Dominant → Tonic relationship within the broader harmonic progression.
The Secondary Dominant (e.g., V⁷/V): Fulfills a dominant function, creating tension that demands resolution.
The Temporary Tonic (e.g., V): The chord of resolution. It functions as a temporary tonic, but it immediately resumes its normal diatonic function (in this case, Dominant) within the home key.
The overall harmonic grammar of Tonic → Predominant → Dominant → Tonic is preserved. A secondary dominant is a chromatic chord that intensifies the move to the next diatonic chord.
Common Progressions
Secondary dominants can be inserted into standard diatonic progressions to create a stronger pull between chords.
Tonicizing the Dominant:
I – V⁷/V – V – I(In C major: C – D⁷ – G – C)Tonicizing the Supertonic:
I – V⁶/ii – ii⁶ – V⁷ – I(In C major: C – A⁶ – d⁶ – G⁷ – C)Tonicizing the Subdominant:
I – V⁷/IV – IV – V – I(In C major: C – C⁷ – F – G – C)Tonicizing the Submediant:
I – V⁷/vi – vi – IV – V – I(In C major: C – E⁷ – a – F – G – C)
Cadence Implications
Secondary dominants are most often found mid-phrase, where they serve to propel the music forward toward the cadence. While they do not define the cadence type themselves, they frequently precede the cadential dominant chord. For example, the progression I – IV – V⁷/V – V leads to a half cadence, but the arrival on V is made more powerful by its preceding secondary dominant. Similarly, in an authentic cadence, V⁷/V can precede the V chord, heightening the tension before the final resolution to I.
Data & Organization Tools
The following table shows which diatonic triads can be tonicized in major and minor keys. The target chord must be a major or minor triad. Diminished triads (like vii° in major or ii° in minor) are not tonicized with secondary dominants because they cannot function as stable tonic chords.
| Key | Diatonic Chord | Secondary Dominant | Example in C major / c minor |
|---|---|---|---|
| Major | ii | V/ii | A major (A–C♯–E) |
| Major | iii | V/iii | B major (B–D♯–F♯) |
| Major | IV | V/IV | C major (C–E–G) |
| Major | V | V/V | D major (D–F♯–A) |
| Major | vi | V/vi | E major (E–G♯–B) |
| Minor | iv | V/iv | G major (G–B–D) |
| Minor | V | V/V | D major (D–F♯–A) |
| Minor | VI | V/VI | C major (C–E–G) |
| Minor | VII | V/VII | D major (D–F♯–A) |
Evidence Bank
Tonicization: The process of making a non-tonic chord sound like a temporary tonic through the use of its dominant. It is a local and fleeting harmonic event.
Secondary Dominant: A V or V⁷ chord that resolves to a diatonic chord other than the tonic. It is the primary agent of tonicization.
Temporary Tonic: The diatonic chord that is the target of a secondary dominant. It serves as a momentary point of stability.
Altered Scale Degree: A note chromatically altered from the home key to create the correct quality (major triad, major-minor seventh) for the secondary dominant. This is the source of the accidental.
V/X Notation: The standard Roman numeral label for a secondary dominant. "V/X" is read as "V of X," where X is the chord being tonicized (e.g., V/V, V⁷/ii).
V/V ("V of V"): The most common secondary dominant. It tonicizes the dominant chord and uses the raised supertonic (^2) as its third, which acts as a temporary leading tone to scale degree ^5.
V⁷/IV ("V⁷ of IV"): A common secondary dominant that tonicizes the subdominant. In a major key, this chord is built on the tonic scale degree (^1) and has the quality of a major-minor seventh chord.
Skill Snapshots
Functional
Progression:
I – V⁷/V – VWhy it works: The V⁷/V creates a powerful, chromatic pull toward the dominant chord, making its arrival feel more significant before it performs its own dominant function.
Progression:
I – V⁶⁵/ii – ii⁶Why it works: Tonicizing the supertonic (ii) reinforces its role as a strong predominant chord, creating a smooth and compelling motion toward the dominant. The inversion creates a smoother bass line.
Progression (in minor):
i – V⁷/iv – ivWhy it works: In a minor key, this progression adds color and drive toward the subdominant, a key predominant chord, before the music proceeds to the cadence.
Voice-Leading
Rule: The temporary leading tone (the third of the secondary dominant) must resolve up by half step to the root of the temporary tonic.
Effect: This resolution is the primary source of the chord's pull and the reason for the required accidental.
Rule: If using a secondary dominant seventh, the chordal seventh must resolve down by step.
Effect: This resolves the dissonance of the seventh smoothly and is essential for proper voice leading.
Rule: Standard part-writing conventions, such as avoiding parallel fifths and octaves, apply when resolving secondary dominants.
Effect: This ensures the independence and clarity of each melodic line through the chromatic passage.
Form
Baseline Phrase: A simple phrase might progress
I – ii – V – I.Contrast: A more dynamic version of the same phrase could be
I – V⁷/ii – ii – V – I. The secondary dominant adds harmonic intensity without changing the phrase's underlying structure.Continuity: Secondary dominants often appear in the middle of a phrase to create a chain of harmonic motion (e.g.,
I – V⁷/vi – vi – V⁷/ii – ii...), propelling the music forward from one diatonic goal to the next.
Common Misconceptions & Clarifications
Tonicization is the same as modulation.
Clarification: Tonicization is a brief, local event. The music remains firmly in the original key. Modulation is a more substantial shift to a new tonal center, often confirmed by a strong cadence in the new key.
Any accidental signals a modulation.
Clarification: A single accidental is very often the sign of a secondary dominant. Analyze the chord containing the accidental to see if it functions as the dominant of the following chord.
Any diatonic chord can be tonicized.
Clarification: Only major and minor triads can function as convincing temporary tonics. Diminished triads (like vii° in major) are too unstable to be tonicized.
The Roman numeral V/V refers to a chord built on the fifth scale degree.
Clarification: The Roman numeral after the slash indicates the root of the temporary tonic. The Roman numeral before the slash indicates the function relative to that temporary tonic. So, V/V is the dominant of the V chord; its root is scale degree ^2.
Summary
Tonicization is a fundamental chromatic technique used to add color and harmonic drive to music without leaving the primary key. It is the process of making a non-tonic chord sound like a temporary tonic. This is most commonly achieved by preceding a diatonic chord with its own dominant, known as a secondary dominant chord. Labeled as V/X or V⁷/X, these chords borrow their notes from the key of the chord they are tonicizing, which requires the use of accidentals to create temporary leading tones. Functionally, a secondary dominant creates a localized D → T relationship that strengthens the progression to the subsequent diatonic chord. By mastering the identification and use of secondary dominants, you can better understand the rich harmonic language of common-practice music.