Seventh chords have four notes, so they can appear in root position or in three different inversions, including a third inversion where the chordal seventh sits in the bass. You label each inversion with figured bass shorthand attached to a Roman numeral: 7 for root position, 6/5 for first inversion, 4/3 for second inversion, and 4/2 for third inversion.
Why This Matters for the AP Music Theory Exam
This topic builds the notation and listening skills you use across the whole course. Once you can spell a seventh chord, find its bass note, and attach the right inversion figure, you can read and write harmonic progressions accurately. Roman and Arabic numeral notation shows up in free-response work that asks you to analyze or notate harmony, and identifying chords in performed music supports harmonic dictation, a skill many students find tricky. Getting comfortable with inversions now sets you up for voice leading with seventh chords in Unit 4.
Key Takeaways
- A seventh chord has four notes (root, third, fifth, seventh), so it can appear in root position plus first, second, or third inversion.
- The inversion is named by which chord member is in the bass: root, third, fifth, or seventh.
- Third inversion is unique to seventh chords and puts the chordal seventh in the bass.
- Figured bass shorthand for seventh chords: 7 (root), 6/5 (first), 4/3 (second), 4/2 (third).
- Attach the figure to a Roman numeral to show scale degree, quality, and bass note all at once (for example, V4/2).
- For aural identification, find the bass note first, then decide whether it is a triad or seventh chord and what quality it is.
Seventh Chord Inversions
A seventh chord is built by stacking thirds: root, third, fifth, and seventh. Because there are four notes, any one of them can sit in the bass, which gives you four possible arrangements.
- Root position: the root is the lowest note.
- First inversion: the third is in the bass.
- Second inversion: the fifth is in the bass.
- Third inversion: the seventh is in the bass. This last one only exists for seventh chords, since triads have no seventh to put on the bottom.
For example, an E major seventh chord (E, G#, B, D#) would be arranged like this:
- Root position: E in the bass, with G#, B, D# above.
- First inversion: G# in the bass, with B, D#, E above.
- Second inversion: B in the bass, with D#, E, G# above.
- Third inversion: D# in the bass, with E, G#, B above.
Inverting a chord can change how it feels in a progression. Moving the bass to a different chord member affects voice leading and the sense of motion between chords, which is part of why composers choose specific inversions.
Using Figured Bass to Label Seventh Chord Inversions
Figured bass (also called thoroughbass) is a system that grew out of Baroque practice. The bass line is written in normal notation, and Arabic numerals, called figures, sit near each bass note to show the intervals above it that complete the chord.
To see where the figures come from, think of a seventh chord in closed position (notes packed as tightly as possible). For a full seventh chord you could list three intervals above the bass. Take a V7 chord in C major, spelled G-B-D-F:
- Root position (G in bass): B is a 3rd above, D is a 5th above, F is a 7th above, so the full figures are 7/5/3.
- First inversion (B in bass, closed as B-D-F-G): figures 6/5/3.
- Second inversion (D in bass, closed as D-F-G-B): figures 6/4/3.
- Third inversion (F in bass, closed as F-G-B-D): figures 6/4/2.
Writing all those numbers every time would clutter the score, so the shorthand below is standard:
| Inversion | Bass note (chord member) | Figured bass shorthand |
|---|---|---|
| Root position | root | 7 |
| First inversion | third | 6/5 |
| Second inversion | fifth | 4/3 |
| Third inversion | seventh | 4/2 |
The figure does double duty: it tells you the chord is a seventh chord and which inversion it is in. If you see ii6/5, you know it is a supertonic seventh chord in first inversion. Pair the figure with a Roman numeral and you communicate scale degree of the root, quality, and bass note all at once, like V4/2.
To connect this to real bass notes, spell a V7 in Bb major. F is scale degree 5 in Bb, and an F dominant seventh chord is F-A-C-Eb. So a V6/5 in Bb has A in the bass (the third), and a V4/3 has C in the bass (the fifth).
Quick check: what is the bass note of a V4/2 chord in D minor? The V of D minor is an A dominant seventh chord (A-C#-E-G), and 4/2 puts the seventh in the bass, so the bass note is G.
Identifying Seventh Chords by Ear
Hearing inversions takes practice, because the intervals shift around when the chord is rearranged. Build the skill in steps.
- Start by telling triads and seventh chords apart. The added seventh gives a fuller, slightly tenser sound.
- Move on to root position versus inverted seventh chords.
- Then work on naming the specific inversion.
A useful strategy is to listen for the bass line first, before worrying about whether you are hearing a triad or a seventh chord. Once you have the bass note, there are only a few chords it could be. Then decide triad or seventh, figure out the quality, and use what you know about progressions to pick the chord that makes sense after the previous one.
Using a keyboard or singing the chord members can help you hear individual intervals more clearly. It is fine to start small: lock in one skill, get comfortable, and add the next layer.
How to Use This on the AP Music Theory Exam
Notation and Analysis
When you analyze a score, find the bass note first, then identify the chord built above it and its quality. Attach the correct figure to your Roman numeral so it shows root, quality, and bass note together (for example, viio7 versus viio4/3). Double-check that you used 4/2 only when the seventh is actually in the bass.
Harmonic Dictation
In aural work, lock the bass line before naming chords. The bass note narrows your choices fast. Then ask whether the sound is a triad or a seventh chord and what quality it is.
Common Trap
Mixing up which figure goes with which inversion. Memorize 7, 6/5, 4/3, 4/2 in order from root to third inversion so you do not stall during dictation or analysis.
Common Misconceptions
- Triads can be in third inversion. They cannot. Only seventh chords have a fourth note (the seventh) to place in the bass, so third inversion is exclusive to seventh chords.
- The figure tells you the root. It does not. Figured bass numbers describe intervals above the bass note, not the root. The Roman numeral identifies the root's scale degree; the figure identifies the inversion.
- 4/2 and 4/3 are interchangeable. They are different inversions. 4/3 is second inversion (fifth in bass) and 4/2 is third inversion (seventh in bass).
- A superscript 7 alone means any inversion. A plain 7 (or 7/5/3) means root position. Inversions need their own figures.
- You must hear every inner voice to name a chord by ear. Often the bass note plus the chord quality is enough to identify the chord and its inversion, especially inside a familiar progression.
Related AP Music Theory Guides
Vocabulary
The following words are mentioned explicitly in the College Board Course and Exam Description for this topic.Term | Definition |
|---|---|
Arabic numerals | Numbers (1, 2, 3, etc.) used in figured bass notation to denote specific intervals above a given bass note. |
bass line | The lowest melodic line in a musical composition that often implies harmonic progressions through its note choices. |
quality | The characteristic sound of a chord determined by the intervals between its notes (major, minor, dominant, half-diminished, diminished). |
Roman numeral analysis | A system of notation using Roman numerals to identify chords and their harmonic function within a key. |
root | The fundamental note of a chord upon which the chord is built. |
scale degree | The position of a pitch within a scale, identified by name or number relative to the tonic. |
seventh chords | Chords built on a triad by adding a note a seventh above the root, creating four-note harmonies with specific qualities. |
third inversion | A chord inversion in which the chordal seventh appears in the bass, occurring only with seventh chords. |
Frequently Asked Questions
What are seventh chord inversions in AP Music Theory?
Seventh chord inversions show which chord member is in the bass: root position has the root, first inversion has the third, second inversion has the fifth, and third inversion has the seventh.
What do 7, 6/5, 4/3, and 4/2 mean?
These are figured bass shorthand for seventh chord inversions: 7 is root position, 6/5 is first inversion, 4/3 is second inversion, and 4/2 is third inversion.
What is a V4/3 chord?
A V4/3 chord is a dominant seventh chord in second inversion, meaning the fifth of the V7 chord is in the bass.
What is a V7 chord?
A V7 chord is a dominant seventh chord built on scale degree 5. In root position, its root is in the bass and the shorthand figure is 7.
Can triads be in third inversion?
No. Only seventh chords can be in third inversion because only seventh chords have a chordal seventh to place in the bass.
How do you identify seventh chord inversions by ear?
Listen for the bass note first, decide whether the chord is a triad or seventh chord, then match the bass note to the chord member to determine the inversion.