17 Diatonic Chords Most chords in tonal music are constructed using only the notes contained within the key.  These are what we refer to as diatonic chords.  If a chord includes a pitch from outside the key, it is generally called an altered or chromatic chord.  It should be mentioned that minor keys, with their three different scale forms, offer many more options for chord structure, within the diatonic setting, than do major keys. There are chords that correspond to each pitch of the scale.  Below are examples of triads and 7th chords constructed on each pitch of both major and minor scales.  Each chord is labeled with a roman numeral -- the upper case roman numerals indicate a major or augmented triad while the lower case indicate either minor or diminished.  The augmented chords will also be labeled with a small plus (+) sign -- the diminished chords with a small circle (o). When a 7th chord has a diminished triad and a minor seventh it is considered half diminished and will be labeled with a slashed circle (Ø) to indicate such.  When a 7th chord has a diminished triad and a diminished 7th it is considered fully diminished and will be labeled with an open circle (o). Example of Diatonic Triads in a Major Key Example of Diatonic 7th Chords in a Major Key Click here to see all the diatonic 7th chords in all the major keys.   Examples of Diatonic Triads in a Minor Key   Pure Minor Harmonic Minor Melodic Minor (Ascending Form) (Note: The descending form of the Melodic Minor scale is the same as the Pure Minor)   Examples of Diatonic 7th Chords in a Minor Key   Pure Minor Harmonic Minor Melodic Minor (Ascending Form) (Note: The descending form of the Melodic Minor scale is the same as the Pure Minor) Click here to see all the diatonic 7th chords in all the minor keys.