Pitch, Scales & Key Signatures

If two notes (pitches) are different, then one note is higher than the other. We can also say how much higher the note is, that is, we can say what the interval between the notes is. The smallest interval between two notes (the nearest that any two notes can be to each other) on a piano keyboard is called a semitone. For example, from C to C# is a semitone - those two keys are right next to each other on the keyboard, just as E is next to F, or B to C. Note that F is not a semitone away from G, because there is a black key in between them - F#. The distance from F to G is therefore two semitones. When two notes are two semitones apart, that distance is described as a whole tone, or simply as a tone. For example, the distance from C to D is a whole tone because there are two semitones in it: the first from C to C# and the second from C# to D. E to F# is a whole tone, F# to G#, A$ to B$, etc.

Notes are written in a variety of shapes on a five-lined stave, also called a staff. Each line and space represents a fixed pitch, so a stave is capable of representing a set of nine notes with these lines and spaces. A note outside the compass of the stave can be represented by using a ledger line. When a clef is placed on the stave, it specifies a particular set of fixed pitches. When a treble clef is placed on a stave, the 5 lines then represent E G B D and F (starting with the bottom line) and the spaces are F A C and E (again starting with the bottom space). When the bass clef is placed on a stave, the lines are G B D F A and the spaces are A C E G. A note's shape represents its length (duration) [see the rhythm page for a list of these], and the position of the note-head determines the pitch.

A scale is an ascending or descending series of notes. The most familiar scale is the major scale. If you play all the white notes on the piano from any C up to the next C you'll hear a C major scale (you may already know it as Doh Ray Me Fah Soh Lah Ti Doh ). You can see that in the major scale the distance from the first note to the second is a whole tone, from 2nd to 3rd a whole tone, 3rd to 4th a semitone, 4th to 5th a whole tone, 5th to 6th a whole tone, 6th to 7th a whole tone, and 7th to 8th a semitone (T T S T T T S). You can also see that we have exactly one of each note, except for the key-note on which the scale starts and finishes (here C).
If we wish to use the major scale starting not on C (the C major scale), but instead on G (the G major scale), we find that we can no longer use only white notes to get the sound of the major scale - playing G A B C D E F G sounds wrong. Because we've started on G, the relationship of tones and semitones has been altered and is now T T S T T S T. We can correct this distribution of tones and semitones by sharpening the F; now when we play the scale we have G A B C D E F# G, and all sounds right. Whenever we play the G major scale we need the F#, so we say that the key signature for G major is F#, or the key signature for G major is one sharp, and write the key signature next to the clef at the start of the line. This indicates that every written F really represents F#. We can repeat this procedure to start a major scale on any of the 12 different notes on the piano, and for each scale (except C major) we must sharpen or flatten one or more of the white notes in order to preserve the arrangement of tones and semitones. For example, the key signature for D major is two sharps - F# and C#.

In addition to the major scale, music often uses a minor scale. There are two versions of the minor, the harmonic minor and the melodic minor. Both minor scales differ from the major in that the third note of the minor scale is a semitone lower than the third of the major. In the harmonic minor the sixth is also lowered a semitone. For example, C major is C D E F G A B C, and C minor (harmonic) is C D E$ F G A$ B C.

The melodic minor scale has an ascending form and a descending form. The ascending melodic minor differs from the major scale only in that the third is a semitone lower; so C minor melodic ascending is C D E$ F G A B C. The descending melodic minor differs from the major in that the third, sixth, and seventh are flattened (lowered a semitone); C minor melodic descending is C B$ A$ G F E$ D C.

The following tables list the major and minor keys (scales) and their key signatures

The order of the sharps in a key signature can be recalled with the mnemonic:

Father Charles Goes Down And Ends Battle

Sharp Keys
Major	Signature	Minor
G	1 sharp	E minor
D	2 sharps	B minor
A	3 sharps	F# minor
E	4 sharps	C# minor
B	5 sharps	G# minor
F#	6 sharps	D# minor
C#	7 sharps	A# minor

The order of flats in a key signature can be recalled with the mnemonic:

Battle Ends And Down Goes Charles' Father

Flat Keys
Major	Signature	Minor
F	1 flat	D minor
B$	2 flat	G minor
E$	3 flats	C minor
A$	4 flats	F minor
D$	5 flats	B$ minor
G$	6 flats	E$ minor
C$	7 flats	A$ minor

C major and A minor each have a key signature of no sharps and no flats.
If you see a piece of music with a key signature of 4 sharps, you know from the sharp mnemonic that those sharps are F#, C#, G#, and D# (Father Charles Goes Down). You know from the table of sharp keys that you are in E major (or its relative minor, C# minor).
In the same way, if your music has a key signature of 5 flats, the flat mnemonic informs you that those flats are B$, E$, A$, D$, and G$ (Battle Ends And Down Goes). You know from the table of flat keys that you are in the key (scale) of D$ major (or its relative minor, B$ minor).