Explained: The Relationship Between The 1-chord and The 4-chord In Structure And Function

Our focus in this lesson is on the relationship between the 1-chord and the 4-chord in the major key.

Understanding the relationship between the chord of the first and fourth tones of the major scale will save you the mental stress of learning both chords separately.

A good step to take towards learning this relationship should be geared towards understanding the chord quality of every scale tone chord in the major key.

Let’s get started.

A Breakdown Of Scale Tone Seventh Chords

There are seven unique tones in the major key. The following tones are in the key of C major:

C:

D:

E:

F:

G:

A:

B:

These seven tones are root notes for the chords in the key (aka – “scale tone chords”) and each of them is associated with a number:

C is the 1st

D is the 2nd

E is the 3rd

F is the 4th

G is the 5th

A is the 6th

B is the 7th

The reference to C:

…as the 1st tone of the C major scale:

…is the reason why the C major triad:

…and the C major seventh chord:

…is known as the 1-chord.

In addition to the 1-chord, there are other chords in the major key and we’ll be highlighting them right away.

Quick Insights On The Quality Of Scale Tone Seventh Chords

Each of the seven scale tones in the major key has its chord; which can be a triad, seventh, or extended chord. Let’s quickly categorize these scale tone chords according to chord quality.

The 1-chord:

…is the C major seventh chord.

The 2-chord:

…is the D minor seventh chord.

The 3-chord:

…is the D minor seventh chord.

The 4-chord:

…is the F major seventh chord.

The 5-chord:

…is the G dominant seventh chord.

The 6-chord:

…is the A minor seventh chord.

The 7-chord:

…is the B half-diminished seventh chord.

Attention: To learn more about this, I recommend our 500+ page course: The “Official Guide To Piano Playing.” Click here for more information.

The Relationship Between The 1-chord And The 4-chord

The goal of this lesson is to show you the relationship between these two scale tone chords:

The 1-chord

The 4-chord

Let’s look at the structural and functional relationship between these two chords in the key of C major.

The Structural Similarity Between The 1-Chord And The 4-Chord

The 1-chord is the C major seventh chord:

…and the 4-chord is the F major seventh chord:

Both chords are similar in structure and this is because they are of the same chord quality.

“Let’s Look At Their Intervallic Components…”

Here’s the distance between the first and third chord tones of both chords:

The interval between C and E (which are the first and third tones of the C major seventh chord):

…is a major third interval and so is the interval between F and A (which are the first and third tones of the F major seventh chord):

Here’s the distance between the first and fifth chord tones of both chords:

The interval between C and G (which are the first and fifth tones of the C major seventh chord):

…is a perfect fifth interval and so is the interval between F and C (which are the first and fifth tones of the F major seventh chord):

Here’s the distance between the first and seventh chord tones of both chords:

The interval between C and B (which are the first and seventh tones of the C major seventh chord):

…is a major seventh interval and so is the interval between F and E (which are the first and seventh tones of the F major seventh chord):

Structurally, the 1-chord and the 4-chord are unmistakably the same chord and that’s why they have the same quality at the triadic, seventh, and ninth level of harmony and here’s the implication:

The C major triad and F major triad are structurally the same:

The C major triad:

The F major triad:

The C major seventh and F major seventh are structurally the same:

The C major seventh:

The F major seventh:

The C major ninth and F major ninth are structurally the same:

The C major ninth:

The F major ninth:

Now that we’ve seen the structural similarity between both chords, let’s go ahead and look at their functional differences.

Attention: To learn more about this, I recommend our 500+ page course: The “Official Guide To Piano Playing.” Click here for more information.

The Functional Difference Between The 1-Chord And The 4-Chord

The 1-chord is also known (to music scholars) as the tonic chord while the 4-chord is known as the sub-dominant chord.

The difference between the 1-chord and the 4-chord is in their tonal function. Irrespective of the structural similarity between the 1-chord and the 4-chord, the 4-chord cannot take on the tonal function of the 1-chord and vice-versa.

The function of the tonic chord in the major key is different from the function of the subdominant chord.

Submission: Although chord substitution makes it possible for any chord to be replaced by a related or foreign alternative, the tonal function of a scale tone chord is what distinguishes it from every other scale tone chord and this is sacrosanct.

Final Words

From all what we’ve covered in this lesson, I’ doubly sure that you’ve seen that the 1-chord and the 4-chord are structurally the same chord, even though they are functionally different.

In a subsequent lesson, we’ll take this to another level with the concept of the “1-4” idea substitution.

See you then!

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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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