Getting Started
Building upon your knowledge of three-note chords, or triads, we now explore the richer sonorities of four-note chords. By adding a note a seventh above the root of a triad, we create a seventh chord. These chords introduce a new level of harmonic complexity and tension, forming the backbone of tonal harmony and voice leading.
What You Should Be Able to Do
Identify the five common qualities of seventh chords from a musical score.
Aurally distinguish between major seventh, major-minor seventh, minor seventh, half-diminished seventh, and fully-diminished seventh chords.
Construct the five common qualities of seventh chords on any given root.
Define a chordal dissonance and identify the chordal seventh in any seventh chord.
Describe the inherent resolution tendency of a chordal seventh.
Key Concepts & Analysis
Our primary lens for understanding seventh chords is their internal tension and resolution, a core concept of voice leading. Unlike triads, which can be entirely consonant, all common-practice seventh chords contain a dissonance that creates a forward drive in the music.
The Chordal Seventh as a Dissonance
A seventh chord is a chord consisting of a triad plus a note forming the interval of a seventh above the chord's root. This added note is called the chordal seventh.
In tonal music, the chordal seventh is considered a chordal dissonance. A chordal dissonance is a chord member that is harmonically unstable and possesses a strong, natural inclination to resolve to a more stable tone. The chordal seventh almost always resolves by moving down by step (a second) into the next chord. This predictable movement is a fundamental principle of voice leading, creating smooth connections between harmonies.
The Five Qualities of Seventh Chords
The character of a seventh chord is determined by the quality of its underlying triad and the quality of the seventh above the root. There are five qualities of seventh chords commonly found in music.
Major Seventh (M7 or MM)
Construction: A major triad with a major seventh above the root.
Example: C-E-G-B.
Aural Character: Bright, rich, and often described as "wistful" or "jazzy." The dissonance between the root and the major seventh is present but relatively mild.
Major-Minor Seventh (Mm7)
Construction: A major triad with a minor seventh above the root. This is the most common type of seventh chord, often called the "dominant seventh."
Example: C-E-G-B♭.
Aural Character: Tense, restless, and unstable. It contains a tritone (an augmented fourth or diminished fifth) between the third and the seventh (E and B♭ in the example). This interval creates a strong pull toward resolution, making the Mm7 chord a powerful driver of harmonic motion.
Minor Seventh (m7 or mm)
Construction: A minor triad with a minor seventh above the root.
Example: C-E♭-G-B♭.
Aural Character: Dark, smooth, and less dissonant than the major-minor seventh. It is a very common sonority, often found on the supertonic (^2) and mediant (^3) scale degrees.
Half-Diminished Seventh (ø7 or dm)
Construction: A diminished triad with a minor seventh above the root.
Example: C-E♭-G♭-B♭.
Aural Character: Highly dissonant, tense, and unstable. Like the Mm7 chord, it contains a tritone, giving it a strong need to resolve. It is most commonly found on the leading tone (^7) in a major key.
Fully-Diminished Seventh (o7 or dd)
Construction: A diminished triad with a diminished seventh above the root.
Example: C-E♭-G♭-B♭♭.
Aural Character: Extremely dissonant, tense, and dramatic. This chord is built entirely of minor thirds, creating a unique, symmetrical sound. It contains two tritones, making its pull toward resolution exceptionally strong. It is most commonly found on the leading tone (^7) in a minor key.
Data & Organization Tools
This table summarizes the construction of the five common seventh chord qualities.
| Chord Quality | Symbol | Triad Quality | Seventh Quality | Example on C |
|---|---|---|---|---|
| Major Seventh | M7 | Major | Major 7th | C-E-G-B |
| Major-Minor Seventh | Mm7 | Major | minor 7th | C-E-G-B♭ |
| Minor Seventh | m7 | minor | minor 7th | C-E♭-G-B♭ |
| Half-Diminished Seventh | ø7 | diminished | minor 7th | C-E♭-G♭-B♭ |
| Fully-Diminished Seventh | o7 | diminished | diminished 7th | C-E♭-G♭-B♭♭ |
Evidence Bank
Major Seventh Chord (M7): A major triad plus a major seventh. Found diatonically on ^1 and ^4 in major keys.
Major-Minor Seventh Chord (Mm7): A major triad plus a minor seventh. The diatonic dominant seventh chord (V7) in both major and minor keys.
Minor Seventh Chord (m7): A minor triad plus a minor seventh. Found diatonically on ^2, ^3, and ^6 in major keys.
Half-Diminished Seventh Chord (ø7): A diminished triad plus a minor seventh. The diatonic leading-tone seventh chord (viiø7) in major keys.
Fully-Diminished Seventh Chord (o7): A diminished triad plus a diminished seventh. The diatonic leading-tone seventh chord (viio7) in harmonic and melodic minor.
Chordal Seventh: The fourth member of a seventh chord, positioned a seventh above the root.
Chordal Dissonance: A note within a chord, such as the chordal seventh, that is unstable and requires resolution.
Resolution of the Seventh: The standard voice-leading procedure where the chordal seventh moves down by step into the subsequent chord.
Skill Snapshots
Functional:
ii7 - V7 - Iin C major: Dm7 - G7 - C.IV - V7 - iin a minor: d - E7 - a.viiø7 - Iin G major: F#ø7 - G.
Voice-Leading:
Rule: The chordal seventh is a dissonance. → Effect: It creates harmonic tension that propels the music forward, demanding resolution for stability.
Rule: The chordal seventh resolves down by step. → Effect: This creates a smooth melodic connection in one voice part, guiding the listener's ear through the harmonic progression. For example, in a G7 to C chord progression, the F (the seventh) in the G7 chord will resolve down to E in the C chord.
Rule: The tritone within a Mm7 chord is highly unstable. → Effect: The two notes of the tritone resolve with strong, predictable motion (e.g., in G7, the B resolves up to C and the F resolves down to E), creating a powerful sense of arrival at the tonic.
Form:
Baseline Phrase: A musical phrase ending on a stable tonic triad (I) feels complete, creating an authentic cadence.
Contrast: A phrase ending on a V7 chord creates a half cadence. The unresolved chordal seventh leaves the phrase feeling open and incomplete, creating an expectation of continuation.
Continuity: The resolution of the V7 to I across the end of one phrase and the beginning of the next provides powerful formal closure, linking the two phrases together through the satisfaction of harmonic tension.
Common Misconceptions & Clarifications
Confusing M7 and Mm7: The only difference is the seventh. A major seventh (M7) has a major seventh above the root (e.g., C-B), while a major-minor seventh (Mm7) has a minor seventh (e.g., C-B♭). Their sounds and functions are very different.
Confusing ø7 and o7: Again, the difference is the seventh. A half-diminished chord (ø7) has a minor seventh, while a fully-diminished chord (o7) has a diminished seventh. This single half-step difference creates a distinct aural character and is a crucial distinction.
Assuming all sevenths are the same: The term "seventh chord" is a category, not a single sound. The specific quality (M7, Mm7, m7, ø7, o7) dramatically changes the chord's emotional character, level of dissonance, and typical function.
Forgetting the resolution: The chordal seventh is not a static note. It is an active pitch with a clear tendency to move down by step. Identifying the seventh also means anticipating its likely path of resolution.
Summary
Seventh chords are four-note harmonies built from a triad and an additional note a seventh above the root. The five essential qualities—major seventh, major-minor seventh, minor seventh, half-diminished, and fully-diminished—are defined by the specific combination of the triad and the seventh interval. The added seventh is a chordal dissonance, an unstable tone that creates harmonic tension. This tension is a primary driver of forward motion in music, as the chordal seventh has a strong, predictable tendency to resolve downwards by step into a more stable chord tone. Mastering the identification and aural recognition of these five qualities is fundamental to understanding harmonic language.