Ask A Music Teacher: What Are The Most Important Seventh Chords In The Major Key?

If you’re interested in learning what the most important seventh chords to learn in the major key are, you are on the right page.

Attention: This lesson is not for absolute beginners. You can only continue with this lesson if you have learned and mastered triads and seventh chords already and are just interested in additional information on seventh chords.

As your music teacher for today, I’ll be starting out on the next segment by refreshing your mind on seventh chords, before taking you by the hand and walking you through the classification of seventh chords according to their importance.

Are you ready? Alright, see you in the first segment!

A Short Note On Seventh Chords

It’s easy to understand what seventh chords are if you’re familiar with intervals.

Seventh chords are chords that (when played in root position) the highest-sounding chord tone is a seventh above the root. For example, the regular C major seventh chord (in root position):

…has B as the highest-sounding chord tone:

…which is a seventh above the root (C):

So, it is the seventh interval between C and B:

…when the C major seventh chord:

…is played in root position that justifies the name seventh chord.

Just like every other seventh chord, the C major seventh chord consists of four chord tones:

C is the root:

E is the third:

G is the fifth:

B is the seventh:

The major key is replete with seventh chords and in the key of C major:

…it includes (but isn’t limited to) the following:

C major seventh chord:

E minor seventh chord:

G dominant seventh chord:

Now that we’ve refreshed our minds on seventh chords, let’s go ahead and classify seventh chords according to their importance in the major key.

Classification Of Seventh Chord Types According To Their Importance

Before I go any further, permit me to say that all seventh chord types are very important and none of the seventh chords you know or have learned in past lessons are less important from an absolute standpoint.

However, we’re looking at things from the microcosm of the major key and truth be told, there are only four seventh chord types in the major key and here they are in no particular order:

The major seventh

The minor seventh

The dominant seventh

The half-diminished seventh

…and we’ll be classifying them in terms of their importance and relevance to the major key.

Also note that before seventh chords (in importance) are diatonic triads: major, minor, and diminished triads. So, I’m NOT saying that these seventh chords are important than any of the major, minor, and diminished chords in the major key.

I’ll emphasize this more in the final segment.

First In Importance: The Dominant Seventh Chord

The most important seventh chord in the major key is the dominant seventh chord and the term dominant is derived from the technical name of the fifth tone of the scale.

So, the dominant seventh chord is basically the seventh chord of the fifth tone of the scale and in the key of C major:

…where the fifth tone is G:

…adding an extra chord tone (in third intervals) to the G major triad:

…(which is F):

…produces a seventh chord (G-B-D-F):

…and because it’s the seventh chord of the fifth tone of the scale, it’s called the dominant seventh chord:

Dominant:

…fifth tone of C.

Seventh chord:

…encompassing a seventh interval from G to F.

The dominant seventh chord is considered to be the most important seventh chord in the major key and this is because of its role in the establishment of the major key.

The strongest progression in the major key remains the movement from the dominant seventh chord to the 1-chord:

G dominant seventh chord:

C major chord:

…and there’s no other seventh chord in the major key that can come close to taking the place of the dominant seventh chord in chord progressions.

Beyond the dominant seventh in the major key, there are chromatic dominant seventh chords known as secondary dominant seventh chords that are irreplaceable when it comes to passing chords and modulation.

Could this be why the term seventh chord basically means dominant seventh? For example, when you say G seventh, you’re making reference to the G dominant seventh chord:

…and not any of these seventh chord varieties:

G major seventh chord:

G minor seventh chord:

G half-diminished seventh chord:

So, that’s it with the most important seventh chord in the major key.

Second In Importance: The Major Seventh Chord

There are two major seventh chords in the major key and they are formed off the first and fourth tones of the scale. In the key of C major:

…where C and F are the first and fourth tones of the scale:

C:

F:

…the C major seventh chord:

…and F major seventh chord:

…are the major seventh chords of the key.

These seventh chords are important because they resonate the quality of the key and of course you know that we’re in the major key, so, playing major seventh chords in the major key will resonate the quality of the key.

Playing the 1-chord (the C major seventh):

…as a major seventh chord is what actually defines the key we’re in; and that’s a major key — specifically the key of C major:

That’s it with major seventh chords, the second most important seventh chord type in the major key.

Third In Importance: The Minor Seventh Chord

The minor seventh chord is a contrasting chord quality to the major seventh chord and that’s what makes it the third in importance.

There are three minor seventh chords in the major key and they are associated with the second, third, and sixth tones of the major scale.

So, in the key of C major:

…we’ll have minor seventh chords built off the following tones:

D:

E:

…and A:

That’s the D minor seventh chord:

…the E minor seventh chord:

…and the A minor seventh chord:

So, those are the minor seventh chords and they are third in importance in the major key.

Fourth In Importance: The Half-Diminished Seventh Chord

Lastly, we have the half-diminished seventh chord — the 7-chord in the major key. In the key of C major:

…the 7-chord is the B half-diminished seventh chord:

Although this seventh chord type is rarely played, it’s still the upper-structure of the dominant ninth chord. For example, the G dominant ninth chord:

…has the B half-diminished seventh chord:

…as its upper-structure.

In certain occasions, the B half-diminished seventh chord:

…can be played as the rootless voicing of the G dominant ninth chord:

In popular music genres like Gospel and Jazz, the half-diminished seventh chord is played on its own as a 7-chord and it sounds as a great option to the chromatic mediant chord:

Final Words

The most important chords in the major key are the primary chords (the three major triads formed off the first, fourth, and fifth tones of the major scale) and they are followed by the secondary chords (every other triad in the major key.)

Seventh chords are not as important as these primary and secondary chords in the major key.

Inasmuch as we’re considering the dominant seventh chord as the most important seventh chord in the key, primary chords (major triads) still come before every known seventh chord type. I’m saying this because nothing can be more important than the primary chords of a key.

But when it comes to seventh chords, the dominant seventh chord is the most important seventh chord in the key.

Special thanks to Jermaine Griggs for the opportunity given to me to share this valuable information with you and don’t forget to share this lesson on all social media.

All the best and see you in the next lesson.

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Chuku Onyemachi

Head of Education at HearandPlay Music Group

Onyemachi "Onye" Chuku is a Nigerian musicologist, pianist, and author. Inspired by his role model (Jermaine Griggs) who has become his mentor, what he started off as teaching musicians in his Aba-Nigeria neighborhood in April 2005 eventually morphed into an international career that has helped hundreds of thousands of musicians all around the world. Onye lives in Dubai and is currently the Head of Education at HearandPlay Music Group and the music consultant of the Gospel Music Training Center, all in California, USA.

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