I. Intro to Chords

II. Triads and Inversions

III. Sus Chords

IV. Sixth Chords

V. Seventh Chords

VI. Extensions

VII. Add chords and Alterations

VIII. Bass and Polychords

IX. Modern and Chromatic Chords

Part V: Seventh Chords

Here’s where things start to get really interesting. As you might have guessed, 7^th chords use the 1, 3, 5, and 7^th tones of the major scale (or accidentals of those tones), which gives it its name. This can be seen more clearly below.

Remember how we constructed triads part II? Well it’s the same idea. We will start with the Major 7^th:

A Major triad was constructed based on the Major third being on the bottom and the minor third on top. This only includes the 1, 3, and 5 degrees of the scale, so we need another tone. Let’s add another third. Since we want this to be a Major 7^th, what should we add? A Major third of course.

For a little difference, let’s use D as our root note instead of C as has been used earlier:

[Picture showing Major 7^th construction using thirds]

Watch that key signature! Remember we are in D Major right now, so we have C# and F# as part of the scale. Notice how the Major 7^th is constructed using the 1, 3, 5, and 7^th tones of the Major scale as mentioned earlier.

The next type of seventh chord we will look at is the minor 7^th. Recall the minor triad. Minor third on the bottom, major third on top. Same idea this time, but we must add another minor third on top now since it’s a minor 7^th.

[Picture showing minor 7^th construction using thirds]

The minor 7^th is built off of the 1, b3, 5, and b7 of the major scale.

Next we will look at the Dominant 7^th. This particular chord has high importance in music in general and has almost innumerous applications in chord progressions and altering moods. It is a highly important chord for all types of Western music.

The Dominant 7^th starts off with a major triad, but has a minor third on top instead of the expected major third of the Major 7^th. So in summary a dominant 7^th has a Major third on the bottom, a minor third in the middle, and a minor third on top.

[Picture showing Dominant 7^th construction using thirds]

The Dominant 7^th is formed off of the 1, 3, 5, and b7 of the major scale.

The next type of 7^th chord we will look at is the diminished 7^th. Much like the diminished triad, it is first formed with two minor thirds on stacked. Now we add yet another minor third on top to give it the quality of the diminished 7^th. You should be getting the hang of this by now.

[Picture showing diminished 7^th construction using thirds]

The diminished 7^th is formed from the 1, b3, b5, bb7 of the major scale.

Finally we have the half-diminished 7^th chord. It starts out as a diminished triad as expected, however, now we must add another third, a major third. The half-diminished 7^th chord is formed by a minor third on the bottom, minor third in the middle, and major third on top.

[Picture showing half-diminished 7^th construction using thirds]

The half-diminished 7^th is formed off of the 1, b3, b5, and b7 of the major scale.

There seems to be something missing...shouldn’t there be an augmented 7^th chord? Try it yourself. You will see that adding a major third on top of an augmented triad just takes you back to the root an octave higher.

However if you add a minor third on top of the augmented triad instead of a major third you do get a chord. A dissonant sounding chord too and it is indeed the augmented 7^th chord. This is actually a part of the set of uncommon 7^ths we will look at in a minute after this summary chart.

Basic Types of 7^th Chords:

The alternate notations are the only ones I suggest you use to avoid confusion. A lot of alternate notations seem to appear for 7^th chords and tend to confuse people who are not so familiar with the ideas behind them. The alternates really shouldn't cause any confusion and might even help you to remember how the chords are formed.

And now, an explanation of the some the more irregular/advanced seventh chords.

Remember sus chords from part IV? They are coming back to haunt you so make sure you know what they are.

First we will look the 7sus4 chord. This is no more than a Dominant seventh chord with a suspended 4^th. 1, 4, 5, b7.

[Picture showing 7sus4 chord]

7sus2 doesn’t even need explaining if you understand sus chords in triads. It’s the same idea. 1, 2, 5, b7.

[Picture showing 7sus2 chord]

The next we will look at is the m/maj7 chord. The “/” (slash) notation is not explained until part IX. But the basic idea you should is that this is formed from a minor third on the bottom and two major thirds on top. The idea of its function and formation will be fully discussed in that section as well. 1, b3, 5, 7.

[Picture showing m/maj7 chord]

Remember that 7^th chord we discussed earlier which was built off of an augmented triad and another minor third? Well here it is, the 7^th sharp 5 chord. A dominant chord with a sharped fifth is all it is. 1, 3, #5, b7. This is the augmented 7^th chord.

[Picture showing 7sharp5 chord]

So what’s the compliment to the chord above? The 7^th flat 5 chord. It isn’t all composed of the typical thirds that were used in the other seventh chords, but like the sus chord, it has a major second in its form. 1, 3, b5, b7. Notice this is again based on the dominant chord...are you starting to see how important the dominant is.

[Picture showing 7flat5 chord]

There are technically two other 7^th chords than should be in this section, but since they are a part of the 9^th chords described in the next section we will have to wait until then to discuss them. Now, below is a summary of the more irregular 7^th chords.

Advanced Types 7^th Chords:

Sometimes the + and – symbols are used instead of sharp and flat respectively. I find this notation to be only necessary with the 7 sharp 5 chord since it’s actually related the augmented chord which also used the + sign. Try to use the symbols in the 4^th column over the alternates, but just be aware that alternates do indeed exist. I would avoid the -- symbol if possible.

Also, be sure to remember what the Perfect 4^ths and Major 2nds are. Look way back in the first section on intervals in the lessons on melody.

Lastly we will touch the concept of inverted 7ths. It would be a good idea at this point to go refer to section III on triad inversion if you have forgotten anything.

The basic idea is exactly the same. But in this case the 1, 3, 5, AND 7 can be the bass note. This yields a total of 3 inversions for 7^th chords. All seventh chords can be inverted and it’s probably not so useful to memorize the intervals that are formed except for those of the Dominant 7^th chord. In any case, they are summarized below for reference if they are needed.

We will use C as the example to make it easier. Obviously C won’t always be the key you are in, but it will make it easier if you are confused or need a comparison of some sort.