subject: Guitar Lesson -- Understanding Keys Part 1 [print this page] What is a "key"? A simple way to define it can be to say that a key is a collection of notes and chords that tend to sound well together. These notes and chords center around the letter name of the key. But how does this happen?
Music, although played and sung emotionally, is a logical, and mathematically perfect language. This logic and perfection is the reason why certain combinations of notes work well together.
Keys begin from something called a scale. There are lots of different types of scales, but keys can normally be thought of as coming from either major or minor scales. We will first learn about major scales by starting with another scale - the chromatic scale.
The chromatic scale is also known as a 12-tone scale. It is also called a half-step scale because the distance (or interval) between each note or tone is 1/2 step.
A A#/Bb B C C#/Db D D#/Eb E F F#/Gb G G#/Ab A....
Note that some notes have two names. Whether you call a note A# (A sharp) or Bb (B flat) for example,depends on whether you are raising the "A" note 1/2 step, or lowering the "B" note 1/2 step. Also, note that the chromatic scale repeats itself over and over, so that I could have started this scale from any letter name.
All scales have step formulas associated with one. The formula for the chromatic scale is: 1/2 + 1/2 + 1/2 + 1/2 + 1/2 + 1/2...... etc. Really understanding the chromatic scale is one of the "keys" to understanding keys.
The major scale also has a step formula, and it is 1 + 1 + 1/2 + 1 + 1 + 1 + 1/2. All major scales use this formula. Also, the major scale has certain rules that must be followed when constructing any of them:
1. You MUST use every letter - no repeats except that the first and last letter will be the same.
2. You must use the formula.
Let's start with the C major scale. First, we must use every letter:
C D E F G A B C
Now we have to apply the formula to see if there are any sharps or flats: (The dots (.) are there for spacing and have no other significance)
C...D... E... F... G... A... B... C
...1...1...1/2...1....1....1...1/2
Now we have to ask ourselves what is 1 step higher than C? We already know that we MUST use the letter D here, but we don't know yet is whether there will be any sharps or flats. If we look at the chromatic scale, we see that the letter D is in fact 1 step (adding half steps -1/2 + 1/2 = 1). Now we know that the first two notes of this scale are C, and D. If you apply the step formula to the rest of the scale, you will find that no further adjustments are necessary. The C major scale therefor is:
C D E F G A B C
This C major scale can be thought of as the key of C
Let's look at another major scale - the G major scale. First, rule number 1 - use every letter:
G A B C D E F G
Next, apply the formula:
G...A...B...C.. D...E...F.. G
..1... 1..1/2..1...1..1.. 1/2
When we go through this note by note, we find that we do not have to make any adjustments to this scale until we reach the letter F. F needs to a be 1 step above E. It is not - it is only 1/2 step, so we need to change the F to an F#. Why F# and not Gb? We are forced to because of rule number 1 - use every letter. So, the G major scale ends up looking like this:
G A B C D E F# G
This G major scale can be thought of as the key of G.
You should construct all the major scales on your own and become familiar with them. It would even be helpful to memorize them. In part 2 of this series, we will look at building chords from the notes of these scales.
