5.2 The vi (VI) Chord

The vi (VI) chord, built on scale degree 6, can work two ways in a tonal phrase: as a tonic substitute that expands the tonic area, or as a weaker predominant chord that leads toward the dominant. Its most common exam use is the deceptive progression, where V moves to vi instead of resolving to tonic.

Why This Matters for the AP Music Theory Exam

This topic sharpens the harmonic thinking you need when you analyze progressions, write four voices, and listen for chord function. Knowing how vi behaves helps you label harmonic function accurately in both performed and notated music, which shows up in harmonic analysis and contextual listening. The deceptive progression (V to vi) is a recognizable sound, so being able to hear and explain it supports both aural and written tasks where you identify what a chord is doing inside a phrase.

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Key Takeaways

• The vi (VI) chord is the submediant, built on scale degree 6. It can act as a tonic substitute or as a weaker predominant chord.
• As a tonic substitute, vi shares two notes with the tonic triad, so it can expand the tonic area (for example I-vi-V-I).
• As a weak predominant, vi often flows into ii or ii6, as in I-vi-ii6-V7-I.
• A deceptive progression happens when V is followed by a chord other than tonic, most often vi. As a cadence, this creates a sense of "not finished yet."
• Function depends on context. The same Roman numeral can do different jobs depending on what surrounds it.
• vi is a relatively weak chord, so you usually see it in root position.

How the vi Chord Works

All chords have a harmonic function, and that function comes from both how the chord sounds and where it sits in a progression. The most common phrase shape is tonic-predominant-dominant-tonic (T-PD-D-T). Tonic feels stable and "at home." Predominant chords (IV and ii in major, iv and ii° in minor) pull away from tonic and lead into the dominant. Dominant creates tension that wants to resolve back to tonic.

The submediant fits into this picture in more than one way.

vi as a Tonic Expansion

The submediant is only one chord tone away from the tonic, so vi/VI can stand in for tonic in some spots. In a progression like I-vi-V-I, the vi moves the music gently before the dominant arrives without creating a real predominant section.

Two things to remember:

• vi is a fairly weak chord, so it usually appears in root position. In first inversion it can sound like a tonic chord with a wrong note.
• You generally do not see vi sandwiched between two tonic chords the way some V or vii° inversions are used, partly because vi can also act as a weak predominant.

vi as a Weak Predominant

The submediant can also pull away from tonic, which is why it is sometimes called a weaker predominant. It flows smoothly into the supertonic. A common phrase might be:

I-vi-ii6-V7-I

Here vi leads toward ii6, which then leads to the dominant.

Deceptive Progressions and Deceptive Cadences

A deceptive progression has the dominant chord followed by a chord other than tonic, typically the submediant. As a cadence, it starts like an authentic cadence with a V chord but does not resolve to tonic. Think of authentic cadences as periods and deceptive cadences as commas: they leave you expecting more. Composers often use a deceptive cadence to push one phrase into the next. The V-to-vi move sounds a little surprising because the ear expects V to resolve to I.

Reading vi by Context

The submediant has several possible jobs, so you cannot always sort it into a single fixed category. Use context to decide.

• If tonic chords are followed by vi and there are no clear predominant chords after it, hear vi as a tonic expansion and group it with the tonic area.
• If vi is directly followed by a predominant chord, especially ii or ii6, label vi as a weak predominant.
• If vi is preceded by V at the end of a phrase, it is most likely a deceptive cadence.

This is the idea behind contextual analysis: you interpret each chord by its job inside the progression rather than assigning one permanent function to every Roman numeral. Heuristics still help. A V or vii° near the end of a progression usually has dominant function, and an opening tonic chord usually has tonic function. But the surrounding chords are what confirm the role.

How to Use This on the AP Music Theory Exam

Harmonic Analysis

• When you see vi, check what comes right after it. vi before ii/ii6 leans predominant; vi after an opening tonic with no predominant leans tonic expansion.
• Label V-vi at a phrase ending as a deceptive cadence.

Contextual Listening

• Train your ear for the V-vi sound. The expected resolution to tonic does not arrive, which gives the phrase an unfinished feeling.
• Listen for whether you hear "home, tension, home" or just "home, home." That tells you whether a chord is really functioning as dominant or as a passing/expansion chord.

Part Writing

• Keep vi in root position in most situations, since first inversion can blur into a tonic chord.
• In a deceptive resolution, lead the voices smoothly so the leading tone resolves correctly even though the bass does not move to tonic.

Common Trap

A V-vi at a cadence is not a weak authentic cadence and not a mistake. It is a deceptive cadence, and you should label it as such.

Common Misconceptions

• "vi always belongs in the tonic category." Not true. It can be a tonic substitute or a weaker predominant. The chords around it decide.
• "vi can replace the whole predominant section." It cannot. When vi expands the tonic, you simply do not hear a separate predominant section; that is different from vi doing the predominant's job.
• "A deceptive cadence is just a failed authentic cadence." It is a deliberate choice. The V moves to a non-tonic chord, usually vi, to keep the music moving forward.
• "Every V chord functions as dominant." Inversions like V4/3 can act as a passing chord between tonic chords, so the bass motion and context can give it a tonic-area role instead.
• "vi works fine in any inversion." Because it is a weak chord, you usually keep it in root position.

Practice Check

Write three short progressions that use the submediant in different ways: vi as tonic expansion, vi as a weak predominant, and V-vi as a deceptive progression. Label the tonic, predominant, and dominant areas in each progression, then explain how the surrounding chords determine the function of vi.

Related AP Music Theory Guides

• 5.1 Adding Predominant Function IV (iv) and ii (ii0) to a Melodic Phrase
• 5.6 Cadential 6/4 Chords
• 5.5 Cadences and Predominant Function
• 5.7 Additional 6/4 chords
• 5.4 The iii (III) Chord
• 5.3 Predominant Seventh Chords