• # Who Else Wants To Know The Differences Between A “7-chord” and A “7th chord”?

I’ll show you the difference between a 7-chord and a 7th chord in this lesson.

Someone might be thinking “the difference between a 7-chord and a 7th chord are as clear as crystal” and wondering why this lesson is necessary.

“Alright! Picture This…”

In the key of C major:

…is the “B-D-F-A” chord:

…a 7th chord or a 7-chord?

But after we’re done looking at 7th chords side-by-side with 7-chords; and differentiating both of them in such a way that you’ll never mistake one for the other you’ll be able to answer the above-given question.

Let’s get started.

## A Breakdown On The 7-Chord And The 7th Chord

A good way to start this lesson is to define or explain both terms — “7-chord” and “7th chords” — and the intent is basically to refresh your mind if you’re already acquainted with both terms or for the sake of those who aren’t familiar with the terms.

So, let’s quickly look over the 7-chord.

### The 7-Chord — Explained

Every tone of the scale is associated with a unique number in the number system. The chord of the 1st tone of the scale is associated with the “number 1” and is described as the 1-chord.

So, the 7-chord is the chord of the 7th tone of the scale and it’s associated with the “number 7.”

In the key of C major where the 7th tone of the scale is B:

C major:

7th tone (B):

…any scale tone chord formed on B is described as the 7-chord.

“Here’s The 7-chord In The Key Of A Major…”

In the key of A major:

…the 7-chord is the G# diminished triad or the G# half-diminished seventh chord:

G# half-diminished seventh chord:

So, the term 7-chord describes the chord of the 7th tone of the scale in any key you’re in.

### “What Is A 7th Chord?”

When the interval between the lowest and highest sounding notes in a chord (played in root position) is a 7th interval, such a chord is said to be a 7th chord.

It should be well-known to you that chords are traditionally formed using third intervals. For example, the C major triad:

…consists of third intervals:

C to E:

E to G:

A third above G is B:

B:

…produces a chord that spans from C to B (“C-E-G-B”):

Due to the fact that the interval between C (the lowest-sounding note) and B (the highest-sounding note) is a 7th interval, consequently, “C-E-G-B” is a 7th chord.

Every other chord that encompasses a 7th interval (when played in root position) is a 7th chord.

## Top Two Differences Between The 7-chord And The 7th Chord

There are a variety of differences between the 7-chord and the 7th chord. However, we’ll be looking at the top two differences in this segment.

### #1 Difference — “Cardinal Vs Ordinal”

The 7-chord is cardinal while the 7th chord is ordinal.

Cardinal numbers include the following:

1, 2, 3, 4, 5, 6, 7, etc.

…while ordinal numbers include:

1st, 2nd, 3rd, 4th, 5th, 6th, 7th, etc

The understanding of the basic difference between an ordinal number and a cardinal number can help you differentiate between the 7-chord and the 7th chord.

Here’s why:

7 (in the case of the 7-chord) is cardinal

7th (in the case of the 7th chord) is ordinal

So, if you know the difference between 7 and 7th, it would help you understand the second difference.

### #2 Difference — “Position Vs Size”

When you hear “the 7-chord” the first thing that should come to your mind should be position, as opposed to “the 7th chord” when size should come to mind.

The 7-chord is the chord of the seventh tone of the scale in any key you’re in. So, “7” is associated with the position of the chord in the key and is entirely different from the 7th.

Always associate the “7th” with the size of a chord because a 7th chord (when played in root position) encompasses a seventh interval from its root to its highest-sounding chord tone.

I hope this helps.

## Final Words

In the case of “B-D-F-A” chord (that we encountered at the beginning of this lesson):

“B-D-F-A” is a 7-chord because it’s the chord of the 7th tone of the C major scale:

…which is B:

…and any chord associated with the 7th tone of the major scale is a 7-chord.

“B-D-F-A” is ALSO a 7th chord because the interval between its lowest and highest-sounding notes (which are B and A):

…is a 7th interval and all chords that span a 7th interval (when played in root position) are 7th chords.

The following two tabs change content below.

#### Chuku Onyemachi

Head of Education at HearandPlay Music Group
Hello, I'm Chuku Onyemachi (aka - "Dr. Pokey") - a musicologist, pianist, author, clinician and Nigerian. Inspired by my role model Jermaine Griggs, I started teaching musicians in my neighborhood in April 2005. Today, I'm privileged to work as the head of education, music consultant, and chief content creator with HearandPlay Music Group sharing my wealth of knowledge with hundreds of thousands of musicians across the world.