Before we start this chapter, be warned: the theory can get quite involved. Don't worry if it doesn't all sink in at the first reading, this is something that you can come back to at leisure.
So far, we have looked at the key of C major and seen that the notes C D E F G A B C can be used to make the four note chords Cmaj7, Dm7, Em7, Fmaj7, G7, Am7, and Bm7b5. We will now look at what happens with other keys.
Let's make a scale starting with G, using all the white notes on the piano.
G A B C D E F G
Analysing the intervals between these notes gives us:
G-A tone
A-B tone
B-C semitone
C-D tone
D-E tone
E-F semitone
F-G tone
or T, T, S, T, T, S, T. This is the same as the pattern of intervals we saw in the C major scale, except for the last two intervals, which are the wrong way round. If we raise the seventh note in this new scale, from F to F# (F sharp), then the last two intervals look like this:
E-F# tone
F#-G semitone.
So the pattern is now the same as that in the C major scale. This scale, not surprisingly is called G major, and it looks like this:
G A B C D E F# G.
We can build three or four note chords on this scale just as we did with C major, and we will get the same series of chord types.
I - GBDF# - Gmaj7
II - ACEG - Am7
III - BDF#A - Bm7
IV - CEGB - Cmaj7
V - DF#AC - D7
VI - EGBD - Em7
VII - F#ACE - F#m7b5
So the simple I-VI-IV-V progression in G would be G Em C D, which would fit in with Heart and Soul and all those other tunes we mentioned in part 1. To compare the two keys, listen to Heart and Soul in C and Heart and Soul in G. You should notice that the two tunes are the same, except that the one in G is at a higher pitch than the one in C.
If we are playing a piece which is entirely in G major, we will not play a single F note (F natural), but we are likely to play an F#. To make it easier to write and read sheet music for such a piece, we might use a key signature, which looks like this:
The sharp sign # is placed on the line for the note F. This key signature means that whenever an F is written in the music, even if it is a lower or higher F note than the one written on the line shown, the performer should play F#. This is the key signature for the key of G major.
Here are two more examples of major scales.
D major: D E F# G A B C# D
F major F G A Bb C D E F
Notice that in D major, we have to have two sharpened notes to keep the pattern T-T-S-T-T-T-S. In F major we must have a flattened note, Bb or B flat, which is a semitone lower than B, in order to keep the same pattern.
This raises an interesting question: if we've got a black note in our scale, how do we decide whether it's a sharp or a flat? Why is the fourth note in F major called Bb not A#? The answer is that when we work out the notes in a scale, we must use all seven letters of the alphabet, A - G. We then put in accidentals (sharps and flats) to make the intervals fit the correct pattern, starting from the root note.
Try working out one or two other major scales and see what accidentals you need to put in, or in other words, find the key signature for that key. The complete list of key signatures is as follows:
C major - No sharps or flats
G major - F#
D major - F#, C#
A major - F#, C#, G#
E major - F#, C#, G#, D#
B major - F#, C#, G#, D#, A#
F# major - F#, C#, G#, D#, A#, E#
C# major - F#, C#, G#, D#, A#, E#, B#
F major - Bb
Bb major - Bb, Eb
Eb major - Bb, Eb, Ab
Ab major - Bb, Eb, Ab, Db
Db major - Bb, Eb, Ab, Db, Gb
Gb major - Bb, Eb, Ab, Db, Gb, Cb
Cb major Bb, Eb, Ab, Db, Gb, Cb, Fb
Count them up and we have C major, seven sharp keys and seven flat keys, making fifteen in all. We only have twelve notes, so where did the extra three come from?
We must remember that, Cb = B, Gb = F#, and D flat = C#, so the scales for these notes represent the same notes, even if the names for those notes are different. We could actually continue these series, to include G#, D#, A#, E# and B# in the sharp keys and Fb in the flat keys, but this would involve using double sharps (written x) and double flats (bb) in the key signatures, and so those keys are not often used.
Pairs of notes such as C# and Db are called 'enharmonic equivalents' which means that they are the same note, but are used in different harmonic situations.
You might like to study the patterns found in the key signatures; there are many. For example, if you start with one of the sharp keys, you can find the key signature for the key which is a fifth (seven semitones) higher by taking the original key signature and adding the sharp for the seventh note in the new scale (which was the fourth note in the original key). With the flat keys, you can find the key signature for the key a fourth (five semitones) higher (or a fifth/seven semitones lower) by taking the original signature and flattening the fourth note in the new key (which was the seventh note in the original key).
A helpful way to remember which notes get sharpened or flattened in the key signatures is the phrase:
Father Charles Goes Down And Ends Battle (for the sharps)
or
Battle Ends And Down Goes Charles' Father (for the flats).
As I said at the beginning, don't worry if you haven't absorbed or memorised all of this section - just come back and re-read it when you feel like it.
In part six, we are going to look at minor keys and the chords that they contain.
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