Note names as seen on the musical staff
C D E F G A B
This is probably the most important scale in the context of music. Even when the others are being discussed, it seems that this one will either be alluded to or directly referenced in some way, shape, or form.
Of course, you also have the accidentals, so a more complete list might look like:
C, C#/Db, D, D#/Eb, E/Fb, F, F#/Gb, G, G#/Ab, A, A#/Bb, B/Cb
Note, or pitches in terms of frequency
| C | 261.6256 Hz |
| C#/Db | 277.1826 Hz |
| D | 293.6648 Hz |
| D#/Eb | 311.1270 Hz |
| E/Fb | 329.6276 Hz |
| F | 349.2282 Hz |
| F#/Gb | 369.9944 Hz |
| G | 391.9954 Hz |
| G#/Ab | 415.3047 Hz |
| A | 440 Hz |
| A#/Bb | 466.1638 Hz |
| B/Cb | 493.8833 Hz |
This assumes A440 as the reference pitch frequency, and spans a single octave in 12-Tone Equal Temperament (12-TET).
Simple intervals
This seems to be derived from the musical staff naming scheme mentioned earlier
| unison | C |
| minor second | Db |
| major second | D |
| minor third | Eb |
| major third | E |
| perfect fourth | F |
| augmented fourth tritone diminished fifth | F# Gb |
| perfect fifth | G |
| minor sixth | Ab |
| major sixth | A |
| minor seventh | Bb |
| major seventh | B |
Here, we use C as the root just as an example.
Notice that I don’t use ‘/’s here, eg. Db/C# or Eb/D#. That’s because the letters used are linked to the interval name. A “second” has to use the second letter. So if I’m starting from C, that would be the letter D. A “third” has to use the third letter (E), a fourth has to use the fourth letter (F), and so on.
The accidental placed next to the letter then depends on whether the interval is major, minor, perfect, augmented, or diminished, and also the root note.
A major third with C as a root note is E, while a minor third with C as a root is Eb. If I change the root though to say, C#, a major third ends up being E#.
In 12-TET, the different intervals are some specific number of steps (or semitones) away from the root.
| Interval | # of semitones up from root |
|---|---|
| unison | 0 |
| minor second | 1 |
| major second | 2 |
| minor third | 3 |
| major third | 4 |
| perfect fourth | 5 |
| augmented fourth tritone diminished fifth | 6 |
| perfect fifth | 7 |
| minor sixth | 8 |
| major sixth | 9 |
| minor seventh | 10 |
| major seventh | 11 |
| octave | 12 |
Beyond this you’ll see roman numerals used to denote chords built on top of intervals.
When you’re in a scale, let’s say the major scale in the key of C, the simple way to build chords is with the notes that are in that scale.
C Major Scale
C D E F G A B
A basic chord is typically built using every other note within the scale. For a triad, you’d take three such notes. For example, C E G is such a triad, and so is G B D.
The Roman numeral naming convention for chords within a scale takes the in-scale position of a note and represents it with a roman numeral. The intention however is to see these as chords, not just as notes.
Roman Numerals and Chords
C D E F G A B
becomes
I ii iii IV V vi vii°
The uppercase roman numerals say that the chord is a Major chord, where a major triad chord, for example, is one where the third note is four semitones up from the root note, and the fifth note is three semitones from the third note (also seven semitones from the root). A major third and then a minor third on top.
The lowercase roman numerals say that the chord is a minor chord, where a minor triad, for example, is one where the third note is three semitones up from the root, and the fifth note is four semitones up from the third note. A minor third and then a major third on top.
The degree symbol ‘°’ means “diminished”. This just means that the third note is three semitones up from the root, and the fifth note is three semitones up from the third note. A minor third and then another minor third on top.
All of this happens automatically within the scale, as long as you stay within that scale when playing your chords.
When using the major scale, the first (I) triad is always a major triad, the second (ii) triad is always a minor triad, and so on, and the seventh (vii°) triad is always a diminished triad regardless of what key you’re in. Again, as long as you stay in-scale.