Diatonic scales are usually played and written in groups of 8 notes, so that they sound finished. The 8th note is the same as the 1st note, but an octave higher or lower.
A, B, C, D, E, F, G#, A1 is a correct scale, but
A, B, C, D, E, F, Ab, A natural is not a correct scale, because the letter name A has been used twice: once as A flat and once as A natural. (Even though you might think that G# and Ab are the same note, they aren’t!)
We talk about diatonic scales as being in a certain key, for example, in "C Major". Most of the scales you will have played up to now will have been diatonic scales. They are the most common type of scale in Western classical music.
You need to know how to write all the major, minor harmonic and minor melodic scales, with up to 6 sharps or flats in the key signature. You are asked to write scales starting on the tonic, which is the technical name for the first note of the scale.
Tones and Semitones
All diatonic scales have something in common; they have a defined pattern of tones and semitones.
Imagine a piano keyboard: two neighbouring keys (whatever colour) are semitones :
E to F is a semitone and B to C is a semitone. A to B flat is one too, and so is G to G sharp .
If you take two notes with one note between them, you’ll have found a tone:
C to D is a tone, as are E to F sharp , D to E and B flat to C.
All major scales are made up with the following pattern, where T=tone and S=semitone:
Here are two examples:
G Major and F# Major
If you’ve ever wondered why we need notes like E sharp when F seems to be the same note, you’ll see that we need them in keys like F sharp major!
If you write a major scale with a key signature, there are no accidentals to add.
Minor Harmonic Scales
All minor harmonic scales have the following pattern, where 3S=three semitones:
D Minor Harmonic and F Minor Harmonic
Minor harmonic scales use the same notes on the way down.
If you write a harmonic scale with a key signature, you always have to add one accidental. In an ascending scale it is the 7th note, in a descending scale it is the 2nd. It could be a natural, sharp or double sharp sign, but is never a flat sign.
Here is F minor harmonic written with a key signature.
Minor Melodic Scales
Minor melodic scales are a little more difficult, because they have one pattern on the way up and different pattern on the way down:
Minor melodic ascending: T-S-T-T-T-T-S
Minor melodic descending: T-T-S-T-T-S-T
For example, here is a scale of C Melodic Minor:
Notice that on the way up we have A natural and B natural, but on the way down we have A flat and B flat.
If you write an ascending melodic scale with a key signature, you always have to add two accidentals, (natural, sharp or double sharp signs), to the 6th and 7th notes.
F minor melodic ascending, with 2 accidentals.
If you write a descending melodic scale with a key signature, there are no accidentals to add.
F minor melodic descending, with no accidentals.
We use “technical” names to talk about each note of the diatonic scale, instead of saying “first note”, “third note” and so on. You need to learn these technical names because there are often general knowledge questions about them in Grade 5 Theory!
Technical names are worked out from ascending scales. For example, in C major ascending, the second note we write is D, so D is the supertonic in C major. If we write out the scale of C major descending, the second note we write is B. But B is not the supertonic. The supertonic is still D; B is the leading note, because it is the 7th note in the ascending scale.
A chromatic scale has 12 notes, and each step of the scale is a semitone, (see above for more about semitones). If you start on a C and play every available note until you arrive at the next C, you have played a chromatic scale. We don’t talk about chromatic scales as being in a particular key; we just talk about the note they start on - and they can start on any note.
Here is an ascending chromatic scale starting on C:
You need to be able to recognise chromatic scales and might have to find a section of a chromatic scale within a piece of music. You don’t have to write out chromatic scales.
To find a section of a chromatic scale, look for a series of notes that are all one semitone apart.
If you’re learning an instrument you’ve probably played all these scales already, but you might have learnt to play them without thinking about the actual notes, (your fingers do the thinking!)
In Grade 5 Theory, you might be asked to write any scale, ascending or descending, either with a key signature or using accidentals. Here are some common mistakes: make sure you don’t make them!
Not using a different letter name for each note.
Not noticing whether the question asks for a key signature or accidentals.
Writing accidentals/key signatures on the wrong space or line.
Writing an ascending scale when the question asks for a descending one, and vice versa. (Remember “D” for “Down” and “Descending”).
Writing a harmonic instead of a melodic scale, or vice versa.
Using the wrong note value - usually you are asked to use semibreves (whole notes).