The Chromatic Scale
The Western Chromatic Music Scale.
What is a Scale?
A Scale just means a related collection of musical sounds (notes), that follow a particular step pattern, in this case semitones.
Western music (that's THE Western hemisphere, not Country and Western :)
uses the what's called the chromatic scale, but there are many others in use around the world.
The chromatic scale is a scale with 12 notes or pitches of sound, each one a calculated musical step apart.
Sound waves vibrate the surrounding air, so sound pitch is measured by its frequency of vibrations, or cycles per second in units called Hertz, (symbol Hz).
The loudness of any sound in measured in decibels, (dB) which is a logorithmic scale, not linear. 10 dB is very quiet, 140 dB will blow your eardrums out! Oops, nearly went off on a tangent there!
Here are the Chromatic Scale notes below...
As you see some notes have two names, these are called enharmonic notes, they are exactly the same notes but may be notated using either the sharp or the flat, you will learn why later.
A semitone represents the smallest musical distance (step) from any fretted note, on a guitar, in our case, to one fret either higher or lower.
Note that between each natural note there is a sharp or flat note, with exception of
B to C and E to F, it's important to remember that right away, otherwise you will be looking for E# and C flat on the fretboard!
As a rule of thumb the Chromatic Scale ascends in sharps (goes up in pitch) and descends in flats.
In written music, sharp and flat notes are never mixed together in the same piece of music, there are either none at all as in the case of the C major key only, or notated with either sharps or flats in the key signature at the beginning of the first stave on the sheet.
Because sharps and flats are never mixed there is some overlapping, and this where things get a little confusing, because it involves using named notes that do not appear to be in the Chromatic scale.
Some notes may be notated as a sharp or a flat to fit in with the scale being used so it appears correctly when written, for a visual idea of what we are talikng about, have a look at the bottom half of the Circle of Fifths diagram.
Also to keep all notation linear, a single named note is never used twice in a scale, for example, you cannot have an A and then A# in the same scale, the A# would be notated as a Bb (flat) so that it correctly follows the note order e.g. G,A,Bb C, otherwise it would read G,A,A#,C and mess everything up!
Okay the good news is these 12 notes of the Chromatic scale are all the notes we will ever use, the bad news is there are many different arrangements of these notes forming other scales that you will be using and thus have to learn, and more good news, these other scale patterns are the same for in each key (in almost every case except the lowest octave in E with standard guitar tuning). Just before leaving chromatic notes, lets have a quick look at octaves as they tie closely together with scales.
As you likely already know by now with guitars, ( and most other instruments) there is more than one of each note on the fretboard.
Some fretted notes have the same pitch as the open string note, because you are playing exactly the same note, but...
taking our C major scale as an example... C,D.E,F,G,A,B,C after the last B note, the scale can be repeated again C,D,E, etc as you move lower (towards the bridge) down the fretboard, thus the next scale is one Octave higher in pitch than the first, and the next is 2 octaves higher than the first etc.
Conversely, to go down the scale, an Octave lower, starting from a C note, the scale is played in reverse order, but going down in pitch, toward the guitar nut.
Most standard guitars are capable of playing at least 4 octaves.
You can learn the theory and the history behind the chromatic scale here.