Chord Progressions, Root Motion & Inversions
- Explain functional root motion and the standard progression flow
- Read figured-bass symbols to determine a chord’s inversion
- Use first- and second-inversion triads idiomatically
Functional flow and root motion
Tonal progressions move with purpose: tonic → predominant → dominant → tonic. The strongest connection between chords is root motion by descending fifth (V → I, ii → V), which drives the circle-of-fifths chain vi → ii → V → I. Root motion by descending third (I → vi) tends to be smooth and connective, while motion by second (IV → V) is strong but needs care to avoid parallels. The dominant almost never falls back to a predominant — that would run the functional flow backward.
Figured bass and inversions
Figured bass numbers show the intervals above the bass note, which reveals the inversion. For triads: root position is 5/3 (written blank), first inversion is 6 (the bass is the chord’s third), and second inversion is 6/4 (the bass is the chord’s fifth). For seventh chords: root position is 7, first inversion 6/5, second inversion 4/3, and third inversion 4/2. Combined with a Roman numeral, V6/5 means a first-inversion dominant seventh.
The four uses of the 6/4 chord
A second-inversion (6/4) triad is unstable — the fourth above the bass is treated as a dissonance — so it appears only in four controlled ways. The cadential 6/4 decorates the dominant at a cadence (I6/4 → V → I). The passing 6/4 harmonizes a stepwise bass line connecting a chord to its inversion. The pedal (neighbor) 6/4 sits over a held bass note. The arpeggiating 6/4 results from a bass leaping among a single chord’s tones. Any 6/4 you write should fit one of these patterns.
A C major triad is voiced with E as its lowest note (E–G–C). Name the inversion and give its Roman numeral with figured bass in C major.
- 1.Identify the chord: the notes C, E, G form a C major triad, which is I in C major.
- 2.Find the bass: the lowest note is E, which is the third of the C major triad.
- 3.A chord with its third in the bass is in first inversion.
- 4.First inversion is figured 6, so the label is I6.
A G major triad is voiced with B as its lowest note (B–D–G). What inversion is this?
Never treat a 6/4 chord as a free, stable harmony. A second-inversion triad must be one of the four idiomatic types (cadential, passing, pedal, arpeggiating). Writing an unprepared 6/4 as if it were root position is a classic error, because the fourth above the bass is a dissonance needing careful handling.
A figured bass of 6/4 beneath a triad indicates which inversion?
Recognize the cadential 6/4 on sight: a tonic 6/4 landing on a strong beat before V, then resolving 6→5 and 4→3 over a held dominant bass (I6/4 → V → I). Many textbooks even label it V6/4–5/3 to show it is really an elaboration of the dominant, not an independent tonic.
Answer the 2 checkpoints as you read.
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