Each type of chord has its own unique structure and sound and can function in multiple ways in a chord progression.
This post will cover the dominant seventh chord’s structure, sound, characteristics and important harmonic functions.
Common fingerings for a dominant seventh chord, along with instruction on how to play them on a guitar with any root note are provided in the post entitled Seventh Chords.
Chord Formula
By way of review, the formula for a dominant seventh chord is 1, 3, 5, b7.
A dominant seventh chord contains the first, third, fifth and flatted seventh degrees of the major scale with the same root note.
For example, a G7 chord contains the notes G, B, D and F — the first, third, fifth and flatted seventh notes in a G major scale (fig.1).
Fig.1
Interval Construction
In terms of interval construction, a dominant seventh chord contains a:
- Major third interval between the first and third notes (fig.2a).
- Minor third interval between the third and fifth notes (fig.2b).
- Minor third interval between the fifth and flatted seventh notes (fig.2c).
- Perfect fifth interval between the first and fifth notes (fig.2d).
- Minor seventh interval between the first and flatted seventh notes (fig.2e).
- Diminished fifth interval between the third and flatted seventh notes (fig.2f).
Fig.2
Sound and Characteristics
Some of the intervals contained in a dominant seventh chord are dissonant (they clash with one another) and give the chord a tense and an unsettled quality.
Tritone Interval
The diminished fifth interval (also called a tritone) between the third and flatted seventh notes is especially dissonant (fig.2f).
The two notes clash with one another and the resulting tension is manifest in a dominant seventh chord.
Diminished Triad
Additionally, the third, fifth and flatted seventh notes in a dominant seventh chord form a diminished triad (fig.3).
Fig.3
A diminished chord is a dissonant chord, in and of itself, and its presence within a dominant seventh chord contributes to the chord’s tension and instability.
Harmonic Tendency
In General
In general, a dissonant or unstable chord is heard as wanting to move to a more consonant or stable one because the tension heard in the dissonant chord is resolved when it moves to the consonant one.
This motion of a dissonant or unstable chord moving to a more consonant or stable one is called a resolution or a cadence.
The Authentic Cadence
Specifically, a dominant seventh chord is heard as wanting to move to the more consonant tonic chord a perfect fifth below it (or a perfect fourth above it). In other words, the V7 chord in any given key is heard as wanting to move to the tonic I chord in that same key.
For example, a G7 chord (the V7 chord in the key of C major) is heard as wanting to move to a C major chord (the I chord).
This chord movement (written V7-I, fig.4) is a specific type of cadence — the authentic cadence — which is the strongest chord movement in music.
The reason the authentic cadence is so strong is that the notes in the dominant seventh chord pull strongly to the notes in the tonic chord.
Fig.4
Analysis of the Authentic Cadence in a Major Key
In general, any given note pulls strongest to the note located half step above or below it and next strongest to the note located a whole step above or below it.
In a dominant seventh chord:
- The third note (B in a G7 chord) pulls strongly to the root note in the tonic chord (C in a C major chord), a half step above it (fig.5a).
- The flatted seventh note (F in a G7 chord) pulls strongly to the third note in the tonic chord (E in a C major chord), a half step below it (fig. 5b).
- The fifth note (D in a G7 chord) pulls strongly to the root note of the tonic chord (C in a C major chord), a whole step below it (fig.5c).
Fig.5
Analysis of the Authentic Cadence in a Minor Key
A dominant seventh chord (V7) also pulls strongly to the tonic minor chord (i) located a perfect fifth below it.
For example, a G7 chord pulls strongly to a Cm chord (fig.6).
This chord movement is written V7-i.
Fig.6
In a dominant seventh chord:
- The third note (B in a G7 chord) pulls strongly to the root note of the tonic chord (C in a Cm chord) a half step above it (fig.7a).
- The flatted seventh note (F in a G7 chord) pulls strongly to the flatted third note in the tonic chord (Eb in a Cm chord), a whole step below it (fig. 7b).
- The fifth note (D in a G7 chord) pulls strongly to the root note of the tonic chord (C in a Cm chord), a whole step below it (fig.7c).
Fig.7
Dominant Seventh Chord Functions
Although a dominant seventh chord pulls strongly to the tonic chord a perfect fifth below it, it doesn’t always move to that chord.
A dominant seventh chord can be followed by any chord (that sounds good) and can function in several different ways in a chord progression.
Functioning Dominant Seventh Chords
A dominant seventh chord’s primary function in a chord progression is to resolve to the tonic chord a perfect fifth below it. So a functioning dominant seventh chord is one that does just that.
Example #1
The progression in fig.8 contains a functioning dominant seventh chord (A7) that resolves to the tonic I chord (D major) a perfect fifth below it.
Fig.8
Example #2
The progression in fig.9 contains a functioning dominant seventh chord (E7) that resolves to the tonic i chord (Am) a perfect fifth below it.
Fig.9
Non-functioning Dominant Seventh Chords
A non-functioning dominant seventh chord is one that does not resolve to the tonic chord a perfect fifth below it. It moves to another chord and the anticipated resolution is avoided.
The progression in fig.10 contains a non-functioning dominant seventh chord (G7) that does not resolve to the tonic chord a perfect fifth below it. It resolves to an Am chord instead.
Fig.10
Static Dominant Seventh Chords
A static dominant seventh chord is one that is heard as the I7 chord in a progression. It doesn’t resolve to another chord.
The I7 chord in a basic 12-bar blues chord progression is an example of a static dominant seventh chord.
The blues progression in fig.11 contains a static dominant seventh chord (E7). It is heard as the I7 chord and doesn’t resolve to another chord..
Fig.11
Secondary Dominant Chords
A secondary dominant chord is a dominant seventh chord that is a perfect fifth above any chord in a progression other than the tonic chord.
Preceding a chord in a progression with its secondary dominant chord creates a sense of anticipation for that chord.
Secondary dominant chords can be functioning or non-functioning.
Functioning Secondary Dominant Chords
A functioning secondary dominant chord is one that resolves to the chord a perfect fifth below it.
The progression in fig.12 is in the key of G major and contains a functioning, secondary dominant chord (F#7).
The F#7 chord is a perfect fifth above the iii chord in the key of G (Bm7) and it resolves to that chord.
Fig.12
Non-functioning Secondary Dominant Chords
A non- functioning secondary dominant chord is a dominant seventh chord that does not resolve to the chord a perfect fifth below it. The anticipated resolution is avoided.
The progression in fig.13 is in the key of F major and contains a non-functioning, secondary dominant chord (A7).
An A7 chord is a perfect fifth above a D or Dm chord but does not resolve to either of those chords. It moves to Bbmaj7 instead.
Fig.13
Application
Understanding a chord’s characteristics, tendencies and various functions will assist you in:
- Analyzing chord progressions.
- Soloing.
- Composing music.
- Understanding more advanced music concepts.
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