September 8, 2020

About the Author: Sonja Joubert

Sonja Joubert
Sonja Joubert is a master pianist classically trained by the late master Mr Josias Van Der Merwe and the late Adolph Hallis. She is also an excellent piano teacher with over 35 years of teaching experience specialising in both jazz and classical piano.

In this article, I will be discussing the 7th chords or jazz chords which are formed on any given major scale or key using the natural notes of the given scale. We will be working from the major scale on which western music is built.

This structure is called the tonal center.

There are 12 possible major or minor keys any particular song can be played in. This is because of the 12 notes on the piano keyboard. This means that anyone of these twelve notes will be the tonal centre or home base.

How can we determine the home key?

There are a few factors you can look at:

  • The key signature is a clear indication:
    Example: when you have a key signature with one sharp (F#) the key will either be G major or the relative minor key which will be E minor.The relative minor key has the same key signature as its relative major key. They are like an older brother and a younger brother or sister – they are closely related.
  • The last note of the song which will normally, (not always though), be the tonic note.
  • The last chord used in the last bar indicates the home key.

Here are the 12 available major (or minor) keys which can be used:

Enharmonic keys are counted as one key. “Enharmonic” means the same key or the same note is played on the piano, except that it’s written differently or musically “spelt” differently. The sound is exactly the same.

  • Key of C
  • Key of Db / C# (enharmonic keys)
  • Key of D
  • Key of Eb
  • Key of E
  • Key of F
  • Key of Gb / Key of F# (enharmonic keys)
  • Key of G
  • Key of Ab
  • Key of A
  • Key of Bb
  • Key of B / Key of Cb (enharmonic keys)

The C major scale

Let us start with using the C major scale so that we do not have to think about using sharps or flats (black notes). C-major, as you most probably know, only consists of white notes.

The scale consists of 8 consecutive notes following one after each other starting from the root note. The notes are numbered from 1 up to 8. In the C major scale you will be starting on the C note moving up stepwise until you once again reach the C note an octave higher:

C D E F G A B C Notes of the C major scale
1 2 3 4 5 6 7 8 Scale degrees or steps
I ii iii IV V vi vii VIII Musical notation of chords

On each of these notes of the scale, you can build a 4 note chord or a seventh chord. In a former article, I explained how to build the 7th chord using 3rds stacked on top of each other. I will in the follow-up article explain in-depth concerning the chords that are built on the major and the minor scale. Melody lines and chords are built on intervals such as 2nds, 3rds, 5ths etc. So let’s look at intervals.

What are intervals?

An interval is a distance between two notes. Firstly in sound and then in the visual picture.

Melodic intervals:

The distance between two notes could be melodical like when you play a melody and the notes move one note to another. It is then called a melodic interval.

Harmonic intervals:

The distance between two notes when they are played together is called a harmonic interval.

The Semi-tone or half step

The smallest interval or distance between western notes or pitches (i.e. the sound of a played note) is called a semi-tone or a half step.

This semi-tone or half step on the piano is the closest note to the next note, making use of the white notes and the black notes. The semi-tone is used to count or work out the rest of the intervals. Please take note that the distance between the two white notes B and C and the two white notes E and F are also a half step.

The whole tone:

The whole tone consists of 2 semitones or two half steps. Thinking in half steps rather than using the technical term “semi-tones” sometimes makes it easier for students to see on the piano, as one can relate the “steps” of notes walking one to another with normal walking or the steps of a ladder. And indeed that is exactly what an interval implies: the walking distance or stepping distance from one note to another made up from a number of these half steps.

Practice to sing the half step and then a whole step which consists of two semi-tones. You will find that it’s quite tricky but vital to hear the difference

The keyboard layout using 12 semitones or 12 notes repeatedly:

The keyboard layout from C up to the C an octave above, is built up of 12 semitones. Twelve notes are used when starting on the C note moving chromatically up until the home note C is played again. The home note is called the root. Moving chromatically means that you play each note the closest on the piano or on any other instrument, playing each semi-tone not skipping any notes, but moving up semi-tone by semi-tone.

Measuring of intervals

Intervals or the measuring from one note to another is always by counting the note which you play as number 1 and counting up or down until you hit the interval you want. If its a 7th, it will be the 7th note which you play in the scale or key you use. Example: a 7th interval from C will be the B note, thus counting up from C as the first note, then D as the 2nd note etc. until you reach the 7th note.

Eight basic intervals

There are 8 basic intervals. Intervals bigger than the octave is called compound intervals like the 3th or 11th etc. For the moment we will only give attention to the simple intervals. Each interval has a very distinct specific sound. Theory on intervals can be quite interesting for the mind, but at the end in playing music, its the sound of the interval that really matters, so do give attention to trying to distinguish the sound of each interval as this will give you an edge when playing both classical and especially jazz piano.

Here are the basic intervals:

  • Unison
  • 2nd
  • 3rd
  • 4th
  • 5th
  • 6th
  • 7th
  • 8th (Octave)

The following are extension intervals (called compound intervals in the classical arena) are used when building jazz chords where the 7th is always used:

  • 9th  (which is like the 2nd played above the octave)
  • 10th (which is the 3rd played above the octave)
  • 11th (which is the same as the 4th played above the octave)
  • 13th (which is the same as the 6th played above the octave) etc.

Intervals can be either perfect or major/minor: *

The Major or Minor intervals:

The 2nd, 3rd, 6th and 7th intervals are either major or minor intervals. Each of these intervals may or can sometimes also be augmented (made bigger by a half step) or diminished (made smaller by a half step) by a half step respectively upwards or downwards.

  • Major seconds are 2 half steps, also called a whole step,
  • Minor seconds are 1 half step.
  • Major thirds are 4 half steps;
  • Minor thirds are 3 half steps.
  • Major sixths are 9 half steps;
  • Minor sixths are 8 half steps.
  • Major sevenths are 11 half steps;
  • Minor sevenths are 10 half steps.

The Perfect intervals:

The unison, 4th, 5th and octave are called perfect intervals and each can be augmented (made bigger by a half step) or diminished (made smaller by a half step). Here are a layout of their make up of half steps used:

  • Perfect Fourths are 5 half steps.
  • Perfect Fifths are 7 half steps.
  • Perfect Unisons are 0 half steps.
  • Perfect Octaves are 12 half steps.

As you can see, each of these has its own set amount of semitones.  As I mentioned before, you can have the knowledge of theory or construction of each interval, but it’s much more important to know the sound and the picture on your keyboard when playing chords than knowing the amounts of semitones, although it would, of course, help you.

* Of course, we also have augmented and diminished intervals, however for the purpose of this article we will not look at them.

Hearing your intervals

If you are practised in interval hearing, you will be able to distinguish the semitone from the tone, or the minor 3rd to the major 3rd.

The interval of a 6th is quite easy to hear with a beautiful sweet expanded sound. The interval of the 6th is when inverted forming a 3rd interval. The interval of a third is easily recognisable and so is the major 7th which has a bitey tension-filled sound. It is worth it to spend some time on familiarising yourself with the sound of each interval.

In playing jazz, knowing the intervals, being able to see them, and especially being able to hear them is of major importance in your chord playing.

The interval consistency or the 4 main jazz chords:

All chords are made up of intervals. As I already mentioned, we literally build up all chords in intervals of 3rds stacked on top of each other. Here is a set out of the 4 main chords and how to think around intervals and the chord.

The Major 7th consists of:

A major 3rd plus a perfect 5th plus a major 7th.

Major 3rd Perfect 5th Major 7th
C to E C to G C to B

To make it easier you can think of having a major triad plus the major 7th added on top.

Major triad chord Major 7th added
C E G plus B

You can also think of it as having 3rds stacked on top of each other. In this case, it will be a major 3rd plus a minor 3rd plus a major 3rd.

Major 3rd Minor 3rd Major 3rd
C to E E to G G to B

The main thing is to be able to “see” the picture of your chord on the keys. You do not want to have to count intervals unless really necessary. It’s best to be able to hear the correct intervals.

The Minor 7th chord consists of:

A minor 3rd plus a perfect 5th plus a minor 7th.

Minor 3rd Perfect 5th Minor 7th
C to Eb C to G C to Bb

To make it easier you can think of having a minor triad with a minor 7th on top.

Minor triad chord Minor 7th added
C Eb G plus Bb

When you think of 3rds stacked on top of each other, the layout will be a minor 3rd, then a major 3rd and a minor 3rd.

Minor 3rd Major 3rd Minor 3rd
C to Eb Eb to G G to Bb

The dominant 7th chord consists of:

The major 3rd plus a perfect 5th plus a minor 7th.

Major 3rd Perfect 5th Minor 7th
C to E C to G C to Bb

It is easier to think of a major triad chord plus a minor 7th on top of it.

Major triad chord Minor 7th added
C E G plus Bb

In the dominant 7th chord the 3rds stacked on top of each other will be a major 3rd + minor 3rd + minor 3rd.

Major 3rd Minor 3rd Minor 3rd
C to E E to G G to Bb

The Minor 7 b5 chord (Diminished or rather a half-diminished chord consists of):

A minor 3rd plus a diminished 5th plus a minor 7th.

Minor 3rd Diminished 5th Minor 7th
C to Eb C to Gb C to Bb

It might be easier to think of a minor triad with a flattened 5th and a minor 7th added on top.

Diminished triad chord Minor 7th added
C Eb Gb plus Bb

The stack of 3rds formed are the following:
A minor 3rd plus a minor 3rd plus a major 3rd.

Minor 3rd Minor 3rd Major 3rd
C to Eb Eb to Gb Gb to Bb

Here is a table of intervals and their make up:

Interval name Example
Unison C to the SAME C
2nd – major 2nd has 2 semitones C to D
(In other words, the first semitone or half step is from C to C# then the second half step is from C# to D. It means that the distance from C to the D note contains 2 half steps. We count chromatically.)
minor 2nd has 1 semitone C to C#
3rd – major 3rd has 4 semitones
minor 3rd has 3 semitones
C to E
C to Eb
4th – perfect 4th has 5 semitones
augmented 4th has 6 semitones
C to F
C to F#
5th – perfect 5th has 7 semitones
diminished 5th has 6 semitones
C to G
C to Gb
6th – major 6th has 9 semitones
minor 6th has 8 semitones
C to A
C to Ab
6th – major 6th has 9 semitones
minor 6th has 8 semitones
C to A
C to Ab
7th – major 7th has 11 semitones
minor 7th has 10 semitones
C to B
C to Bb

Augmenting or diminishing the interval:

  • All the major intervals can be made minor by reducing the interval with a half step.
  • The perfect Intervals can be augmented by adding a half step or made smaller – then called a diminished interval by making the interval a half step smaller. I have given this for you as information, as many students want to understand the building and constitution of intervals.

In the follow-up article, we will be looking at the jazz chords built on each of the steps of the major scale and how to implement them into your jazz playing.

You can view that article here.

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