For the piano/composers: I compose music for the piano in my spare time, and one particular chord that has caught my attention (as one that I like a lot) is the D-F-G chord in C Major.

I have seen Mozart use this chord many times. In particular, his piano sonata in C (No.16 K.545). In both the first and second movements, he uses this chord at the beginning. In the first movement, he plays the I chord, then quickly switches to D-F-G, then back again. I don't know what that chord is. If I had to guess, I would say that it is a V7 chord second inversion without the 3rd? (D-F-G-B, excluding the B). In the second movement, you can see the same thing except in the key of G Major.

Link to the Music Sheet: Sonata in C Sheet Music

What interests me most about that chord in particular, is that it doesn't seem like a full chord change. It seems as though Mozart uses it in the middle of the I chord. It seems like some kind of composing "trick" to me. I have heard in the past about how it is possible to extend chord progressions by switching back and fourth between two chords. For example, ending with V, I, V, I [...] rather than just V, I. Perhaps Mozart was using a technique of some sort to lengthen the I chord and keep it interesting?

And as a last question about the "D-F-G" chord: Is there a particular name for a chord like that? I know that a Csus4 is C-F-G, and Csus2 is C-D-G. I had some thoughts that maybe D-F-G might really be some kind of ii chord variant.

  • 3
    I agree that it's a V7 second inversion. The mediant of the V isn't required.
    – user28
    Jul 23, 2011 at 1:09
  • 3
    Well, also, the mediant of the V is in the right hand in that measure.
    – user954
    Jul 23, 2011 at 2:53
  • 2
    Sometimes a chord is a chord and sometimes it's counterpoint. A C chord moving up and back to D F G is more like a double upper neighbor than a chord change.
    – user955
    Jul 23, 2011 at 3:14
  • "C7 second inversion". Dies with confusion Apr 18, 2013 at 2:41
  • One remark: in the 2nd mvt, m1, if it were f# d c d in l.h., together with r.h. c - d there would be a parallel fifth. Jan 27, 2017 at 17:41

3 Answers 3


There are a few observations that can be made here. First, as others have noted, the sonority is the dominant. Always make sure to take the entire context (including both staves as well as the surrounding sonorities) into account when determining what to call a sonority. In the first movement, as @moberhau mentioned, you do have all members of the dominant seventh chord. The inversion simply facilitates pianistic voice-leading. In the second movement, first measure, again there is a momentary shift to a dominant sonority in the lower staff only. What about entire context? I'm getting to that.

You made an observation that alternating chords can serve just to prolong one harmony. Yes, that is what seems to be happening in both the places you mentioned. The dominant is not truly structural, but rather it prolongs the tonic. There is no larger-scale advancement of the form of the movement that occurs due to the dominant sonority there.

Finally, trust your ears. Even if a particular note is missing or appears not to fit, what does the passage sound like? In both cases you mention, I believe that the sonority sounds like a dominant "in passing," just to prolong the tonic.


It's called (since you ask ) G dominant 7 with no 3rd. In guitarspeak G7/D(no3)

  • I like how you classified G7/D(no3) as "guitarspeak"; it can be instantly interpreted as an interesting piece of additional context; and at the same time it conveys the fact that it would be unusual for someone interpreting Mozart's piece in academic context to ever use this name.
    – fdreger
    May 30, 2022 at 10:14
  • @fdreger - that was nearly 10 yrs ago! But it still stands. How else could it be termed, when the chord is G7 with no 3rd? Seems a lot of site visitors need labels - just like most of humanity.
    – Tim
    May 30, 2022 at 10:35
  • Blame the algorithm :) Every once in a while I get drawn here by some "hot question" link. Today I found a question about chords, downvoted your answer, clicked on the "chord" tag just to see the type of question people ask... and voila, the first thing I clicked had your answer, almost identical to the one I downvoted, but perfectly worded. So I had a laugh, upvoted it (I believe that you have net +9 from me today, not that you care :) ) and took time to comment on the difference between "In guitarspeak it's G7(no3)" and " [...] F7(no3) - [...] is just what it is."
    – fdreger
    May 30, 2022 at 13:08
  • how strange, it doesn't allow me to add "@Tim" in the former comment. A bug?
    – fdreger
    May 30, 2022 at 13:09
  • 1
    @fdreger - since it's my answer, there's no need . Just comment.
    – Tim
    May 30, 2022 at 13:15

A dominant (seventh) chord will generally contain the 3rd. But you're only looking at the LH I think. The melody in the RH is part of the chord too! And as well as the 'rule' that says the 3rd is a defining element of a triad (particularly of a dominant triad) there's one that says that, BECAUSE it's so distinctive, it should only appear once in the musical texture. Rules are made to be broken. But the 'harmony exercise' rules are applicable to a Mozart sonata, because of its period and its simplicity.

  • Apparently, the 3rd (B) is in the melody, so yes, it's not going to appear in the l.h.
    – Tim
    Feb 7, 2017 at 16:37

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