Scales: seven notes and the gaps between them

Most people meet the major scale as do re mi and never find out what makes it that particular set of notes rather than some other set. The answer is short: it is a pattern of gaps, and the gaps are what you are actually hearing.

The pattern

There are two sizes of step. A semitone is the smallest gap on a keyboard, the distance from any key to the one right next to it, black or white. A tone is two semitones.

The major scale goes: tone, tone, semitone, tone, tone, tone, semitone.

Start on C and follow that and you land on the white keys, all of them, in order. That is not a coincidence about the universe, it is a fact about how the keyboard was built. Somebody arranged the white keys so that the pattern comes out on them starting from C.

• C
• D
• E
• F
• G
• A
• B
• C

The two semitone steps are between the third and fourth notes (E to F) and between the seventh and eighth (B to C). Play E then F, then play C then D, and you can hear that one is a tighter squeeze than the other.

Move the pattern and you need black keys

Start on G and apply the same pattern. G, A, B, then a semitone to C, then D, E, and now the pattern wants a tone from E, which gets you to F sharp, then a semitone home to G.

• G
• A
• B
• C
• D
• E
• F sharp
• G

Play it with F natural instead and you will hear it sag right at the end. That seventh note leaning hard into the eighth is a big part of what makes a scale sound finished, and it is why it has the name leading note.

Every key needs its own set of sharps or flats for the same reason, and the order they turn up in is not random. That is what key signatures are about.

The minor scale, and why there are three of them

The natural minor uses the same pattern shifted: tone, semitone, tone, tone, semitone, tone, tone. Starting on A, that lands on the white keys again, which is why A minor and C major are described as relatives. Same notes, different home.

• A minor
• C major

Then things get untidy. Natural minor has no leading note, its seventh is a whole tone below home, so it does not pull. Composers wanted the pull, so they raised the seventh, and that gives harmonic minor. But raising it leaves an awkward tone-and-a-half gap before it, which is hard to sing, so they also raised the sixth going up and dropped both coming down. That is melodic minor.

Three scales is not three rules. It is one problem, solved differently depending on whether you care more about harmony or about the singer.

Take notes away and something strange happens

Remove the fourth and the seventh from a major scale and you are left with five notes that cannot really clash with each other. That is the pentatonic scale, and it is what a handpan and a guzheng are tuned to. It is also why those instruments sound good under a beginner's hands and why they refuse most of the songs in our catalogue.