Seventh Chords and Arpeggios

With the four basic chord types (major, minor, diminished and augmented) under our fingers, it’s time to learn how to start extending them. The next step is learning the “seventh” chords, the theory behind them and how to construct them on the fretboard. In this lesson, we’ll focus on the theory.

What’s In a Name?

So what’s with this “seventh chords” name, anyway? If you recall how we constructed triads, we took the root, third and fifth degrees of the major scale to create the basic major triad. Then we altered the third and fifth notes to get our four basic triads: major, minor, augmented and diminished.

Notice that the notes of each triad come from skipping every other note: root, skip two, three, skip four, five. If we keep going we skip the sixth and move to the seventh. When we add a seventh to a triad we call it a “seventh” (or “7th”) chord (or arpeggio). We also have two different sevenths we can work with: the minor seventh and the major seventh.

So suddenly we have four notes we can deal with, three of which can be altered by moving them a half-step in either direction. The number of combinations starts to get a little dizzying:

3rd 5th 7th Name Comment
major perfect major major 7th Very common, esp. in jazz
major perfect minor 7th (or “dominant 7th”) Very common in all styles
major augmented minor 7+5 (or “augmented 7th”) Mostly a “jazz” chord
minor perfect major minor major 7 Mostly a “jazz” chord
minor perfect minor minor 7 Very common in all styles
minor diminished minor m7♭5 Mostly a “jazz” chord

This isn’t every combination, but these are the most common ones. The naming may seem a little confusing and while there’s (sort of) a method behind the madness, this just might be one of those things you just have to memorize.

A 7th chord/arpeggio without any modifier is assumed to be a dominant seventh composed of the 1st, 3rd, 5th and ♭7th. These are often written like A7, C7, etc.

A major seventh chord/arpeggio is make up of the 1st, 3rd, 5th and 7th degrees. These are written like A maj 7 or, sometimes, A △7.

A minor seventh chord/arpeggio is made up of the 1st, ♭3rd, 5th and ♭7th degrees. These are written like Am7 or A-7.

Logically-speaking, you might think that the term “minor 7th” would mean that only the third is diminished. The reality is that most minor chords found “in the wild” have minor 7ths in them, not major 7ths. The minor triad with a major seventh is a pretty rare chord that comes from a special scale used (mostly) in jazz.

These three chords/arpeggios (7, maj. 7 and min. 7) are the by far the most common ones found in popular music. If you learn nothing else, knowing these forms will help cover a good bit of popular music.

The Theory Behind the Names

At this point, you may be scratching your head wondering how anyone came up with these chords. These were not simply created out of thin air—there is a method behind the madness!

Let’s start with our old friend the C major scale. The notes are C, D, E, F, G, A and B. If we start with C and skip each note to get the first four notes we get C, E, G and B. Those notes are the root, major third, fifth and major seventh.

The next group of notes is D, F, A and C. If we compare those notes to the D major scale (D, E, F♯, G, A, B and C♯) we get the root, minor third, fifth and minor seventh. Remember that when we name chords, scales and arpeggios, it’s always relative to the major scale of the same key.

Here is a list of the entire major scale “harmonized” using this technique:

Notes Degrees Chord/Arpeggio Name
C, E, G, B 1, 3, 5, 7 Major 7
D, F, A, C 1, ♭3, 5, ♭7 Minor 7
E, G, B, D 1, ♭3, 5, ♭7 Minor 7
F, A, C, E 1, 3, 5, 7 Major 7
G, B, D, F 1, 3, 5, ♭7 7
A, C, E, G 1, ♭3, 5, ♭7 Minor 7
B, D, F, A 1, ♭3, ♭5, ♭7 Minor 7 ♭5

Put another way, the order is: 1. major 7 2. minor 7 3. minor 7 4. major 7 5. 7 6. minor 7 7. minor 7♭5

Some interesting things to note about the harmonized major scale:

  • There are three minor 7 chords
  • There are two major 7 chords
  • There is only one 7 chord
  • There is only one m7♭5 chord

If you play these chords in order up the neck it sounds like the major scale, played as chords:

Next Up

Remember that with scales, chords and arpeggios, we’re trying to master three things:

  1. The sound
  2. The theory
  3. The shape on the fretboard

This lesson gives you the theory. In the next lesson we’ll look at the shapes which will help you to start playing them. Playing them is the only way to get the sound in your head. Once you have the sound in your head, you can start making real music with them.

Believe it or not, you will eventually be able to hear a chord and have a pretty good idea of what kind of chord it is. You may not know the exact voicing or if there are any extensions, but seventh chords and arpeggios define the basic “types” that we deal with. Everything else is just adornment.

Until next time, rock on!