Now that we have mastered the Triad in the Harmony of Major and Minor Keys, let’s expand the chord structure further!
Our 3-note Triad is a structure built from a pair of Third intervals.
The Seventh Chord adds an additional Third interval to the basic Triad.
The 7th Chords in the Key of C
Key of A minor
Here we can see the 5 most common 7th Chords used in Music.
The Major 7 Chord is a Major Triad with a Major 7th interval added. It is often abbreviated as Maj7, Ma7, M7.
The Minor 7 Chord is a Minor Triad with a Minor 7th. It is often abbreviated as min7, mi7, m7
The Dominant 7 Chord is Major Triad with a Minor 7th. The name Dominant comes from it being built on the 5th degree of the scale, the V, or the Dominant. This is the most important 7th Chord in Classical Music (also in many other kinds of music). Notice the Tritone (between 3 & 7). This causes the chord to be very active and it strongly needs to resolve its tension. Because it is so common, it is abbreviated simply with a 7, ie G7.
The Half-Diminished 7 Chord is a Diminished Triad with a Minor 7th. In Jazz it is often called the Minor 7 b5 (Minor Seven flat-Five), and is abbreviated ∅7.
The Diminished 7 Chord is a Diminished Triad with a Diminished 7th. It is a structure built of two Tritones, and is symmetrical. This allows for all sorts of interesting harmonic possibilities because the Dim7 doesn’t really belong to a single Key, so it can be used freely to connect chords that otherwise have no direct relationship to one another. We’ll explore many of these possibilites in our studies with Harmony. It is abbreviated as º7, or Dim7.
Inversions of the 7th Chord
G7 in Four Positions
The Root Position
The Chord is built with a 7th up from the Bass note. Technically a 3,5,7 Chord built from the Bass note upwards. Abbreviated simply: 7
The 1st Inversion
With the Inversions of the 7th Chord, we identify them by where the interval of the Second appears in the Chord. Here, between the 5th and 6th up from the Bass note.* Technically a 3,5,6 Chord built upwards from the Bass note. Abbreviated: 6/5
*Notice that we build the chord up from the Bass note- B, not the “Root”- G.
The 2nd Inversion
Here, the Second interval appears between the 3rd and 4th up from the Bass note. Technically a 3,4,6 Chord built up from the Bass note. Abbreviated: 4/3
The 3rd Inversion
Here, the Second interval appears between the Bass note and the 2nd. Technically a 2,4,6 Chord built up from the Bass note. Abbreviated: 2
Remember that as far as the Figures are concerned, the chords are built up from the note in the Bass, not the “Root” of the chord.
These examples are all from the G Dominant 7 Chord, but the same numbered Figures apply to all other types of 7 Chords also.
It might be confusing for you to understand why you have to learn these numbers to describe all these inversions of the same G7 chord. I can say from personal experience that having learned the number system helped my music reading skill greatly. The reason is that it’s much more difficult to see a cluster of notes on the page and immediately be able to see where the root of the chord is and know “oh, this is G7 in the second inversion,” than it is to simply see the bass note, and then know the chord by the intervals stacked on top. It seems confusing and backwards, but I feel that it helps to understand both viewpoints. And really if the system is good enough for Bach, perhaps it’s worthwhile for us to know it as well!
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