Everything You Ever Wanted to Know about 7th Chords

Welcome to LivingPianos.com, I’m Robert Estrin. Today, you’re going to learn everything you ever wanted to know about 7th chords. I recently put out a video about triads. Triads are chords built on thirds containing three notes. 7th chords are kind of an extension of triads. A major triad consists of two different types of thirds: a major third on the bottom and a minor third on top. A minor third on the bottom and a major third on the top gives you your minor triad. A diminished triad consists of two minor thirds. An augmented triad consists of two major thirds.

7th chords contain four notes arranged in thirds.

Like triads, 7th chords consist only of major thirds and minor thirds. Major thirds are four half-steps apart. Minor thirds are three half-steps apart. It’s easy to remember triads because you have two sets of thirds, so there are only four possible combinations. But when you have four notes, how do you remember everything? I’m going to show you such an easy way. It’s kind of like a cheat, but it works, and you’re going to love it!

I’m going to show you the three types of sevenths that are used.

A major 7th is the seventh note of the major scale, a half-step shy of an octave. A minor 7th is a half-step smaller than that, and a diminished 7th is a whole step smaller. Those are the only kinds of sevenths that are used in seventh chords. The rest are just triads. A major triad with a major seventh is a major seventh chord. I think you probably can guess where this is going. A minor triad with a minor seventh is a minor seventh chord. A diminished triad with a diminished seventh is a diminished seventh chord.

Seventh chords, just like triads, are only built on the intervals of thirds.

So you always skip a letter when you see it written on the staff. It’s either all lines or all spaces (as long as the root of the chord is on the bottom). So indeed, the major triad is spelled C, E, G, B. The minor seventh chord is C, E-flat, G, B-flat. The diminished is C, E-flat, G-flat, B-double-flat. That’s right. Because it has to be spelled in thirds, and G-flat to B-double-flat is a third. If it was written with an A, it wouldn’t look right on the page. You wouldn’t identify it as a chord. When you see all the notes on lines or all the notes on spaces, you know it’s a chord. You just have to figure out the accidentals to know what type of chord. There are just two left that you have to learn.

If you have a major triad with a minor seventh chord, you have a major minor seventh chord, which is called dominant.

Why dominant? Because it is built on the fifth scale degree. If you play every other note of the major scale, starting on the fifth note of the scale, it forms a dominant seventh chord or V7. And in sheet music, when you just see 7, written after a letter, it indicates a dominant seventh chord. It is the most popular seventh chord and one of the most important for establishing the key.

There’s one more seventh chord called half-diminished.

How could it be half-diminished? It’s a diminished triad with a minor seventh. That’s your half-diminished seventh chord. It is found natively as VII7. You build a seventh chord on the seventh scale degree, and you have a diminished triad with a minor seventh. Incidentally, the diminished seventh chord is only found natively in the minor as the VII7, assuming it is a harmonic minor scale. The harmonic minor has a raised seventh. That’s where the diminished seventh chord is built. It is an incredibly powerful chord that can be built anywhere and can facilitate modulation and provide deceptive resolutions. It’s a fascinating chord unto itself. I have a video on the diminished seventh chord.

I hope this has demystified seventh chords for you!

Major/major is major. Minor/minor is minor. Diminished/diminished is diminished. Major/minor is dominant. And half-diminished is your VII7, a diminished triad with a minor seventh, VII7 in the major key. That’s it for today I hope this is enlightening for you! And I hope this makes it easy to remember all the seventh chords without having to think about all the possibilities of the three sets of thirds. This breaks it down for you in a very digestible way.
Thanks again for joining me, Robert Estrin, here at LivingPianos.com, Your Online Piano Resource.

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