Second-inversion seventh chord (Sekundakkord)
Third inversion of a seventh chord: the seventh lies in the bass and continues downward.
What it means
The Sekundakkord is the third inversion of a seventh chord: the seventh lies in the bass, and the root stands a second above it. This second gives the chord its name; in figured-bass notation it is designated 2, more fully 4/2.
Musical use
Because the seventh is a dissonance that is resolved downward, and here stands in the bass, the continuation is fixed: the bass falls one step. With the dominant seventh chord this leads into the six-three chord (first inversion) of the tonic, that is, into the position with the third in the bass — the turn from D7 with the seventh in the bass to the tonic with the third in the bass. The close thereby seems soft and inconclusive, rather continuing onward.
This voice leading makes the Sekundakkord a means of leading bass lines stepwise downward. A bass descending from the tonic's root through the dominant's seventh to the tonic's third connects three sonorities in one plain line.
In four-part writing, the Sekundakkord usually contains all four notes of the seventh chord; no doubling occurs, because four notes fall onto four voices. The leading tone lies in an upper voice and rises to the root of the tonic.
The Sekundakkord is to be distinguished from the cluster and from the added second: there the second is a tone colour; here it is the consequence of an inversion and demands resolution.
The Sekundakkord of the dominant seventh chord usually leads into the six-three chord of the tonic, because the seventh in the bass is resolved stepwise downward. In figured-bass notation it stands as 2, 4/2, or 6/4/2. In function theory it is designated with a small 7 under the function symbol. Because the dissonant note lies in the bass, this chord seems especially urgent and hardly works as a point of rest.
Performance practice
Lead the bass note downward and give it weight — it is the dissonance, and the resolution works only if it was audible. Take the following six-three chord more lightly. And take care to lead the leading tone in the upper voice upward, instead of letting it stay put.