Dominant Seventh Chord

A dominant seventh chord is a four-note chord built from a root, major third, perfect fifth, and minor seventh (a major triad plus a minor 7th). Built on scale degree 5 and labeled V7, it creates tension that resolves to the tonic, making it the engine of tonal harmony on the AP Music Theory exam.

What is Dominant Seventh Chord?

A dominant seventh chord is a major triad with a minor seventh stacked on top. From the root you get a major third, a perfect fifth, and a minor seventh, which is why theorists call its quality "major-minor seventh" (Mm7). It fits the CED's definition of a seventh chord, four distinct pitches stacked in thirds on adjacent lines or spaces (PIT-1.O.1).

Here's why it gets the name "dominant." In any major or minor key (with the raised leading tone in minor), the seventh chord built on scale degree 5 naturally comes out major-minor. You label it V7 in Roman numerals. The chord contains two unstable notes that demand resolution. The leading tone wants to rise to tonic, and the chordal seventh wants to fall by step. Together those two notes form a tritone, and resolving that tritone is what makes V7 to I feel so conclusive. In G7 resolving to C major, the B pulls up to C while the F pulls down to E. That built-in tension-and-release is what gives tonal music its sense of forward motion.

Why Dominant Seventh Chord matters in AP Music Theory

The dominant seventh chord lives in two places in the course. In Unit 3 (Topics 3.1 and 3.2), you have to recognize its quality by ear and on the page (LO 3.1.A) and label it with the correct Roman numeral and figured-bass symbols like V7, V6/5, V4/3, and V4/2 (LO 3.2.A, PIT-2.A.1). In Unit 5 (Topic 5.1), it becomes the centerpiece of harmonic function. The CED's core progression is tonic-predominant-dominant-tonic (PIT-2.H.7), and V7 is the chord most often doing the dominant job, with IV (iv) or ii (ii°) set up right before it (PIT-2.H.8). LO 5.1.A asks you to identify and describe harmonic function in both performed and notated music, and spotting the V7 is usually how you locate the dominant area of a phrase. It also matters for part writing, since the leading tone and chordal seventh have strict resolution rules that show up constantly in the harmonization FRQs.

How Dominant Seventh Chord connects across the course

Leading Tone (Unit 3)

The leading tone is the third of the V7 chord, and it's the note that makes the chord pull so hard toward tonic. In voice leading, it typically resolves up by half step to scale degree 1, which is half of the tritone resolution that defines a V7 to I cadence.

Chordal Seventh (Unit 3)

The chordal seventh is the fourth note of any seventh chord, and in V7 it's scale degree 4. It resolves down by step to scale degree 3, no exceptions in AP part writing. Forgetting this resolution is one of the most common point-losers on harmonization FRQs.

Predominant Function: IV (iv) and ii (ii°) (Unit 5)

Predominant chords exist to set up the dominant. The CED's tonic-predominant-dominant-tonic order (PIT-2.H.7) means IV or ii almost always lands right before V7, which is why ii to V7 to I is the textbook way to intensify a key.

Diminished Seventh Chord (Unit 3)

Both chords carry dominant function because both contain the leading tone and the tritone. The difference is the stack. V7 is a major triad plus a minor 7th, while vii°7 is fully diminished (all minor thirds). They often substitute for each other in real music.

Is Dominant Seventh Chord on the AP Music Theory exam?

Expect this chord everywhere. Multiple-choice questions play or notate a chord and ask you to identify its quality (major-minor seventh) or its Roman numeral with the correct inversion symbol (V7, V6/5, V4/3, V4/2). Aural questions test whether you can hear the difference between a dominant seventh and other seventh-chord qualities, especially the major seventh chord. On the free-response side, the part-writing and harmonization FRQs require you to use V7 correctly, which means resolving the leading tone up, resolving the chordal seventh down by step, and placing the chord in the dominant slot of the tonic-predominant-dominant-tonic progression. The sight-singing and dictation sections also lean on V7 because dominant-to-tonic motion defines cadences. If you can't spot or spell a V7 fast, almost every section of this exam gets harder.

Dominant Seventh Chord vs Major Seventh Chord

Both start from a major triad, so they're easy to mix up. The difference is the top note. A dominant seventh adds a minor seventh above the root (G-B-D-F), while a major seventh adds a major seventh (G-B-D-F#). That one half step changes everything. The dominant seventh contains a tritone and sounds tense and unresolved, while the major seventh sounds lush and stable (think jazz ballads). On aural ID questions, listen for the clash and pull of the tritone. If the chord sounds like it needs to go somewhere, it's the dominant seventh.

Key things to remember about Dominant Seventh Chord

• A dominant seventh chord is a major triad plus a minor seventh above the root, which is why its quality is called major-minor seventh (Mm7).

• It occurs diatonically on scale degree 5 in major keys, and in minor keys when you raise the leading tone, and it's labeled V7 in Roman numeral analysis.

• The tritone between the leading tone and the chordal seventh is what creates the chord's pull toward tonic.

• In voice leading, the leading tone resolves up to scale degree 1 and the chordal seventh resolves down by step to scale degree 3.

• V7 fills the dominant slot in the CED's core progression of tonic-predominant-dominant-tonic, usually set up by IV (iv) or ii (ii°).

• Inversions get figured-bass symbols (V6/5, V4/3, V4/2), and you need to read and write all of them for Roman numeral identification.

Frequently asked questions about Dominant Seventh Chord

What is a dominant seventh chord in music theory?

It's a four-note chord made of a root, major third, perfect fifth, and minor seventh, like G-B-D-F in the key of C. It's built on scale degree 5, labeled V7, and resolves to the tonic chord.

Is a dominant seventh chord the same as a major seventh chord?

No. A dominant seventh has a minor seventh on top of a major triad (G-B-D-F), while a major seventh has a major seventh (G-B-D-F#). The dominant seventh sounds tense because of its tritone; the major seventh sounds smooth and stable.

Why is it called a dominant seventh chord?

Because scale degree 5 is called the dominant, and this chord quality occurs naturally when you build a seventh chord on that degree in a major key. The name describes its position and function, not just its sound.

How does a dominant seventh chord resolve?

It resolves to the tonic chord. The leading tone (the chord's third) moves up a half step to scale degree 1, and the chordal seventh moves down by step to scale degree 3. In AP part writing, those two resolutions are required, not optional.

How is V7 different from vii°7 if both have dominant function?

Both contain the leading tone and the tritone, so both pull toward tonic. But V7 is a major triad plus minor seventh built on scale degree 5, while vii°7 is a fully diminished seventh chord (stacked minor thirds) built on the leading tone. The exam tests them as distinct qualities in Unit 3.