Chords and Chord Progressions in Diatonic Major Keys

12/01/06

Much of popular music is composed of harmonies from one diatonic major key.  Therefore, common chord progessions abound in pop music.  Once one determines the characteristic relationships between these harmonies, picking out many of the chord progressions from popular music become a matter of the best educated guess.

The following Q&A outlines the thinking behind the Roman numeUnder The Sun Studios - notation of all of the characteristic chords in one Diatonic Major Key.

Q. How many notes are there in the musical alphabet?
A. There are seven. A, B, C, D, E, F, G

Q. How many notes are there in a key?
A. There are seven.  One of each letter. For example, the Key of C has C, D, E, F, G, A, B and the Key of G has G, A, B, C, D, E, F#.  Note that the only difference between C and G is one note.

Q. How many chords are there in a key?
A. There are seven.  There is one based on each note.

Q.  What is the pattern of chords in a key?
A.  The pattern of chords in a key is designated by roman numeUnder The Sun Studios - s.  Chords in a key are either major, minor, or diminished.  The way that lays out is as follows:  I, IV, V are major chords and are referred to as the primary chords.  ii, iii, vi are minor chords are referred to as the secondary chords.  vii^ο is diminished and isn't really often used in pop music.

Therefore, the pattern of chords is I, ii, iii, IV, V, vi, vii^ο

Major, minor, minor, Major, Major, minor, diminished

Q. How does this apply to the Key of C?
A. In the key of C, the chords are C Major, D minor, E minor, F Major, G Major, A minor, and B diminished.

Q. Can I figure out the key of a song from the chords that are being played?
A. Yes! You can determine the key of a song from as few as 2 chords. For instance, if 2 major chords are found to be one step apart from each other, they are very likely to be IV and V.  For instance, if we have a song with C Major, A minor, F Major, and G Major, We know that F Major and G Major only exist simulataneously in the key of C.  To check this, we can jump one hop in either direction on the Circle of Fifths. In the Key of F, the "G" Chord is G minor and in the Key of G, the "F" chord is F# diminished.  Therefore, the most likely key is C Major. (or, A minor, but that is a discussion for another article.)