More Seventh Chords: The Supertonic 7th

This music theory lesson assumes you understand how to build seventh chords and the basics of diatonic harmony. Those topics can be reviewed here:

It might also be helpful to review the concept of chord substitution in this music theory lesson, where we learn that the supertonic chord (ii) may be used in place of the subdominant chord (IV).

Here is an example from that lesson:

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In the example above, we start with a basic TSDT progression, then substitute the subdominant chord (IV) with the supertonic chord (ii). One chord is not better than the other; these are simply two ways of writing a basic chord progression. Whether you prefer the IV chord or the ii chord is a matter of taste.

The ii7 Chord

Now we’ll add the seventh to the supertonic chord:

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The seventh of the supertonic 7th chord is scale degree one () of the given key. In the voicing above, I put in the soprano so it is easy to see and hear. When the tonic chord moves to the ii7, stays in the same voice as a common tone, then resolves down by step (as all sevenths should!) to the third of the dominant chord.

Something else you should notice is that the ii7 chord is incomplete, that is, it is missing the 5th. In this progression, the fifth of the tonic chord cannot move up to the fifth of the supertonic chord because it would result in forbidden parallel fifths:

As we learned in this music theory lesson, there is nothing wrong with incomplete chords. But in the minor key, the missing fifth lessens the chord’s richness because it is a half-diminished seventh, where the diminished fifth is needed for distinction.

The ii7 Chord in First Inversion

In most traditional music, composers have tended to avoid the root position supertonic seventh in favor of the ii7 chord in first inversion:

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The first-inversion supertonic seventh chord is the best of both worlds: it actually is a combination of the IV chord (F-A-C) and the ii chord (D-F-A). In popular chord charts, you will see this chord indicated as an “Fadd6″ (in C major).

In the progression above, the bass is the same as the I-IV-V-I progression, thus strengthening the subdominant-class function of the ii7 chord.

Also, the presence of the seventh and the fifth (making it a complete chord) provide a richness unavailable in any of the other subdomant-class chords (IV, ii, ii7 in root-position).

Other Inversions of the ii7 Chord

While the first-inversion ii7 chord is the most common, the second and third inversions are also possible:

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Music for Practice and Study

To solidify your understanding of these concepts, you should practice the progressions in a variety of keys, paying close attention to the voice leading. A PDF version of each progression from this lesson, written out in every major and minor key, is available on the Harmonic Progressions page.

Also, analyze the chords of the music you are working on with your instrument. See if you can find examples of the supertonic 7th chord functioning as we discussed in this lesson. If you want a challenge, try analyzing some of the J.S. Bach chorale harmonizations. Bach tends to favor the supertonic seventh chord in first inversion. A great resource for free public domain music is the Petrucci Music Library. You can download the Bach chorale harmonizations here. There are 371 of them, so that should keep you busy for a while!

Other pieces to study are the Mozart and Beethoven piano sonatas. You’ll find that Mozart often uses the supertonic triad in first inversion, while Beethoven favors the supertonic seventh.