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Victoria Williams

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6. Added 7th and 9th Chords in Trio Sonatas

Grade 8 Music Theory - Added 7ths and 9ths in Trio Sonatas

Added 7th Chords

The added 7th chords you are most likely to encounter are the dominant 7th (V7) and supertonic 7th (ii7/ii°7/II7). You might also see an occasional diminished 7th (vii°7b or vii°7).

 7ths table of 7th chords


Theoretically, since a 7th chord contains four notes, and we are writing harmony in three parts, you’ll need to omit something. In V7 and ii7 this will normally be the 5th, and in a diminished 7th chord, it could be the 3rd or 5th.

In practice, the chord is often made complete by the use of melodic decoration. For example, in the first V7 chord in the C major section above, the missing D might be supplied like this:

 7ths missing note added


You may see 7s in the figured bass on chords other than V and ii. They will usually be suspensions – which we’ll explore in the next chapter.

You can easily identify a suspension because it is followed by a short dash.

7ths on 6th degree


Approach and Exit in V7 and ii7

In order to handle a V7 or ii7 chord correctly, it’s not enough just to include the right notes in the chord! In Baroque harmony dissonances were treated in a specific way, so if the added 7th creates an accented dissonance, the approach and exit from the dissonance must also be correct. “Approach” means the note before the dissonance, and “exit” is the note after the dissonance.

For example, in G7, the added 7th note is F. In whichever part the F is written in, you also need to look at the notes before and after the F. In this case, the F of G7 is in the top part:

7ths approach


Chord V7 is normally approached either by a preparation or a leap. Chord ii7 should only be approached by preparation.


If the 7th is “prepared”, it means that it occurs in the previous chord, in the same part. We could prepare the F in the top part like this:Approach by Preparation

7ths preparation

Preparations are often tied to the following 7th, but they don’t have to be.


Approach by a Leap

Chord V7 (but not normally ii7) can also be approached by a leap. A “leap” is a jump upwards of an interval bigger than a 2nd.

Here, the A leaps up to the 7th F, so that’s fine.

7ths leap approach

If you decide to approach a 7th chord by a leap, you’ll need to make sure you know that it’s a V7 and not a supertonic 7th, which means working out the prevailing key at that point (which of course, is something you should be doing anyway!)


7th as Melodic Decoration

7ths which are shown in the figured bass can sometimes be added as melodic decoration (rather than “chord notes”) – particularly when you need to preserve the pattern in a sequence – use your judgement! Here, the added 7th Bb (boxed) is a passing note, to make a sequence with bar 1.

7ths 7th in decoration



You may see chord V moving to chord V7. In this situation, make the root of V move downwards by step to the 7th.

In this example, the prevailing key is E major. The B in the dominant chord moves downwards by step to A, to become the 7th in the following V7 chord.

7ths V V7


II7 (V7) – V7 – I

You may see a series of dominant 7th chords used in quick succession, following the circle of 5ths. For example, in the key of G, the progression A7-D7-G might be found. In this case, A7 is a secondary dominant chord. The best way to deal with this, is to make at least one part move chromatically: C#-C-B in this case.

7ths II7 V7 I


Exit by Step

All 7ths should be quitted by a step downwards. These bars contain three different 7ths, all of which resolve by step in the next chord.

7ths exit by step


Diminished 7th Chords

Diminished 7th (vii°7 or vii°7b) are seen more rarely than the other types of added 7th chord.

They characteristically appear in chromatic progressions, such as the following (prevailing key Bb major):

7ths diminished 7th


Notice how the bass line moves upwards by semitones from D to F, and one of the upper parts moves downwards by semitones (the middle part here, Eb-D-Db-C). The diminished 7th chord is d.


This passage illustrates well the way dissonances are prepared and resolved.

  • Chord a is V7, and the Eb will have either been prepared or approached by a leap in the previous bar.
  • Chord b is tonic first inversion.
  • Chord c is a subdominant Eb major chord, with a prepared 7th D from the previous chord.
  • In chord d, the 7th D moves to Db in the diminished 7th chord. The part moves by a semitone. The G is a harmonic auxiliary note.
  • Chord e is a suspension. The Bb in the top part was prepared in chord d, and the Db from chord d moves by semitone to C.
  • Chord f is the resolution of the suspended Bb onto A.

You’re most likely to see diminished 7th chords used at strategic points in the music, such as at cadences or modulations.


9th Chords

Chords with an added 9th are figured with a 9. You can distinguish them from suspended 9ths, as there is no dash after the figure 9.

The 9th above the bass is, of course, the same as a compound 2nd. Since it’s a dissonant interval, it needs to be prepared in the previous chord. 

9th chord 


In this case, the added 9th is the A, which is prepared in the previous chord, and then repeated.

When you realize a 9th chord, think carefully about the other note you will write, to create the 3rd part. With a root and a 9th, e.g. G-A, if you add the third of the chord, B, you will create quite a clash, since the chord will consist of three consecutive tones (whole steps) G-A-B.


You have various options to avoid this:

  • Add the third as an accented passing note moving to the 9th (like the above example, where the top part has B-A semiquavers (16th notes)
  • Omit the third and add the 5th (D)
  • Omit the third and double the root (G)
  • Put a rest – but only if it makes sense rhythmically.



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