A Deeper Insight On Thirds And Sevenths

The goal of today’s post is to give you a deeper insight on thirds and sevenths.

This post is a sequel to what we covered previously on tenths and sevenths. I consider it appropriate for us to explore the concept of tenths and sevenths from a diatonic perspective because it’ll show us the application of tenths and sevenths in a key that we’re familiar with. In addition to that, it’ll prepare us for the use of thirds and sevenths in chord progressions.

As usual, we’ll be doing it in the key of C major, which is everyone’s favorite.

A Flashback On Tenths And Sevenths

Tenths and sevenths are basically intervals.

An interval is the relationship between two notes [in terms of the distance between them.] – Jermaine Griggs

In a nutshell, it takes two notes to form an interval – whether a tenth or a seventh. A tenth is an interval that encompasses ten degrees of a given scale, while a seventh is an interval that encompasses seven degrees of a given scale.

 A Flashback On Tenths

Using the C major scale:

…a tenth encompasses ten degrees of the C major scale from C to E:

…and believe it or not, the tenth is a large interval (compound interval) that some people find it challenging to play with one hand. Notwithstanding the challenges of playing the tenth, it remains a rewarding accompaniment for your left hand.

Although the tenth (C-E):

…is a compound interval, there’s a simple interval (C-E):

…that is related to it. This simple interval encompasses only three degrees of the C major scale:

…consequently, is called a third.

Tenths can be derived from thirds by expanding the third. Let me show you how to expand the third into a tenth using what I call the octave transposition technique.

Transposition literally means a transfer of position.

Octave transposition is a technique you can expand a third into a tenth with, either by transposing the lowest note to a lower octave, or by transposing the higher note to a higher octave.

C to E:

…becomes a tenth if the lower note (C):

…is lowered by an octave:

…or the higher note (E):

…is raised by an octave:

The relationship between the tenth and the third makes both of them the same thing.

Considering how important thirds are in music, we can also place such importance on tenths. According to Jermaine Griggs, “the third tone of triad determines its quality – whether it’s a major or a minor triad.” Consequently, if a third determines quality, then tenths in the same vein would determine quality too.

There are basically two tenths that are [commonly] used – the major and minor tenths. A major tenth is the skeleton of a major chord, while a minor tenth is the skeleton of a minor chord.

 A Flashback On Sevenths

In the key of C major, a seventh encompasses seven degrees of the C major scale:

…from C to B:

The seventh, unlike the tenth is handy and lies within the compass of the hand.

Just like tenths, sevenths also determine the quality of a chord – whether major or minor. This is not applicable most of the time because 60% of common chord qualities share the minor seventh interval in common.

Tenths and Sevenths In The Key Of C Major

Let’s breakdown the concept of tenths and sevenths to something we can apply in the key of C major.

Tenths In The Key Of C

Here are all the tenths you can build in all the scale degrees in the key of C…

C-E:

…that’s the tenth of the first degree.

D-F:

….the tenth on the second degree.

E-G:

…the tenth on the third degree.

F-A:

…the tenth on the fourth degree.

G-B:

…the tenth on the fifth degree.

A-C:

…the tenth on the sixth degree.

B-D:

…the tenth on the seventh degree.

Now that we have covered these tenths let’s look at their respective qualities.

Quality Analysis Of Tenths In The Key Of C Major

C-E:

…is a major tenth, because in its simple form, C-E:

…is a major third.

Attention: A major third is the relationship between the first and the third tones of a given major scale.

D-F:

…is a minor tenth, because in its simple form, D-F:

…is a minor third.

We also have E-G:

…E-G is a tenth on the third degree of the C major scale, and it’s a minor tenth because E-G:

…in its simple form is a minor third interval.

F-A:

…is a major tenth, because in its simple form, F-A:

…is a major third.

G-B:

…is a major tenth, because in its simple form, G-B:

…is a major third.

A-C:

…is a minor tenth, because in its simple form, A-C:

…is a minor third.

B-D:

…is a minor tenth, because in its simple form, B-D:

…is a minor third.

Altogether, there are three major tenths, and four minor tenths. Major tenths are on the first, fourth, and fifth degrees of the scale, while the minor tenths are on the second, third, sixth, and seventh degrees of the scale.

“Take Note…”

While playing scale degree chords, it’s easy for you to play the left hand part if you can remember that all scale degrees have the minor tenth interval, save the first, fourth, and fifth degrees.

Sevenths In The Key Of C

Let’s look at sevenths in the key of C.

On the first degree of the scale is C-B:

C-B:

…is a major seventh interval because it encompasses the first and the seventh tones of C major scale.
On the second scale degree is D-C:

D-C is a minor seventh because it is a half step smaller than the first and seventh tones of the D major scale:

…which are D and C#:

Lowering D-C#:

…by a half step (to D-C):

…produces the minor seventh interval. We’ll come across other minor seventh intervals as we proceed.

Seven degrees from E:

…is D:

…therefore, E-D:

…is minor seventh interval.
F to E:

…is a major seventh interval.
Seven degrees from G:

…is F:

…therefore, G to F:

…is a minor seventh interval.
Seven degrees from A:

…is G:

A to G:

…is a minor seventh interval.
Seven degrees from B:

…is A:

B to A:

…is a minor seventh interval.

Final Words

In another post, I hope to show you chords that work over tenths and sevenths. Once you master them, you’ll be sounding like that gospel or jazz pianist out there.

If you don’t believe me, check out this 2-5-1 chord progression in the key of C using tenths and sevenths on the left hand.

Chord 2:

Chord 5:

Chord 1:

Take note of the left hand tenths on chords 2 and 1, and the left hand seventh on chord 5. We’ll explore these and more in a subsequent lesson.

Thank you for your time.

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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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