-Below we have what was once a root position G major triad with an extra
note added on top.
-This
F note is a minor 7th above the root note
G. It is therefore considered the 7th of the chord.
-You will notice that we are in the key of C MAJOR. The G note is scale degree 5 in this key.
-This G7 chord is therefore considered to be a V7 chord in the key of C.
-Notice the chord members and their positions:
The
ROOT, the
3rd, the
5th and the
7th.
-The V7 chord contains 2 TENDENCY TONES, that together create a TRITONE:
1-The
3rd of this chord (scale degree 7) wants to resolve UP to scale degree 1.
2-The
7th of this chord (scale degree 4) wants to resolve down to scale degree 3.
-These resolutions will occur when the V7 (DOMINANT) chord resolves to a I (TONIC) chord.
-It is difficult to resolve a ROOT POSITION V7 chord to a ROOT POSITION TONIC CHORD
without breaking some voice leading rules
(parallel 5th or 8ths, for example).
-We therefore often find find that smoother chord progressions can result if we omit one of the chord tones from the V7 chord. Should we do so, your first option should be the
5th of the chord (scale degree 2).
-If you omit the
3rd, the chord loses it's QUALITY (major or minor).
-If you omit the
7th, the chord ceases to be a 7th chord, looses one of it's TENENCY tones and, therefore, a good bit of strength resulting in a less fulfilling CADENCE.
We can also solve some of these issues by using INVERSIONS.
Below, you will see the V7 chord in 3 possible INVERSIONS: 1st, 2nd and 3rd.
Notice that the chord members, ROOT, 3rd, 5th and 7th,
all maintain their functions and should observe the same considerations, when moving to the next chord.