Advanced Keys and Scales
Order of Sharps and Flats
When sharps or flats are added to a key signature, they are added in a specific order. The order of sharps is the reverse order of flats.
| Order: | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| Sharps: | F-sharp | C-sharp | G-sharp | D-sharp | A-sharp | E-sharp | B-sharp |
| Order: | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| Flats: | B-flat | E-flat | A-flat | D-flat | G-flat | C-flat | F-flat |
Every time a sharp or flat is added to a key signature, it changes the order of whole and half steps in the generated scale. They are added in a certain order so that the generated pattern is W-W-h-W-W-W-h, which is the pattern used in major and natural minor scales. Key signatures never have both sharps and flats in them because combining sharps and flats would also disrupt the pattern of whole and half steps.
| C | D | E | F | G | A | B | C | |||||||
| W | W | h | W | W | W | h |
The above is a C major scale. If we add an F-sharp , we change the order of whole and half steps like this:
| C | D | E | F-sharp | G | A | B | C | |||||||
| W | W | W | h | W | W | h |
The pattern is still the same, but the order of whole and half steps does not make a major or minor scale. So, we need to start on a different note to get the correct order for a major or minor scale. The new starting point becomes the new tonic pitch, which shares its name with both the scale and key that have been created by adding the new accidental. For example, if G becomes the new tonic, we are now doing the key of G major, which uses the G major scale. The other option is to make E the new tonic, which would make it an E minor scale, which is used in the key of E minor.
| G major: | G | A | B | C | D | E | F-sharp | G | |||||||||||||||||
| W | W | h | W | W | W | h | W | W | h | W | W | ||||||||||||||
| E minor: | E | F-sharp | G | A | B | C | D | E | |||||||||||||||||
Enharmonics and Note Spelling Within a Key
Previously, we discussed harmonic equivalence simply by saying that C-sharp is the same as D-flat , and so on. Now that we have discussed the way keys are constructed, there are a few more things to say on this topic.
First, the collection of notes (or scale) defined by a key signature includes only one pitch for each letter (A, B, C, D, E, F, G). These pitches may be the natural version of the note (A), the sharp version (A-sharp), or the flat version (A-flat), but there will never be more than one in a given collection. That is, there is no key that includes both A and A-sharp - there is only one version of A in the collection. This fits with the principle that sharps and flats do not exist together in standard key signatures.
In keeping with these enharmonic principles, A and A-sharp should not appear together often, because they do not exist together in a single key. However, B-flat, the enharmonic equivalent of A-sharp, does exist in two major keys along with A: the key of F and the key of B-flat. Therefore, when writing in the key of F or B-flat, it is necessary to use B-flat instead of A-sharp, since B-flat exists in the collection and A-sharp does not.
Modal Scales
Modal Scales Discussion and Examples