In Part One, we saw that the first two diatonic chords of the C major scale are C major and D minor, usually abbreviated to C and Dm. If we analyse the remaining chords in this scale we see the following sequence:
Scale Degree Notes Name
I CEG C major or C
ii DFA D minor or Dm
iii EGB E minor or Em
IV FAC F major or F
V GBD G major or G
vi ACE A minor or Am
vii BDF B diminished or Bº
Notice that the Roman numerals for the major chords (I, IV, V) are in upper case, and the numerals for the minor chords (ii, iii, vi) are in lower case. There are three major chords in the sequence: C major, F major and G major. These are also known as the tonic, subdominant and dominant, or I, IV and V chords. These three major chords form the famous "three chord trick", which underlies a huge number of songs. For example, try singing these songs and playing the chords on your piano/keyboard or guitar.
G C G C
Happy Birthday to you, Happy Birthday to you,
F G C
Happy Birthday dear Fred, Happy Birthday to you
Listen to Happy Birthday to You with these chords
Listen to the chords alone
or
C F C
Michael row the boat ashore, alle - lu - ia
C G C G C
Michael row the boat ashore, alle - lu - u - ia
Listen to Michael Row the Boat Ashore with these chords
or
C F C
Gonna write a little letter, gonna mail it to my local DJ
F C
There's a rockin' little record I want my disk jockey to play
G F C G
Roll over Beethoven, gotta hear it again today
Listen to Roll Over Beethoven. The chords have been 'decorated' with a typical rock and roll riff in this excerpt - see if you can follow the chord changes.
There are thousands more songs like this: most Chuck Berry songs, blues songs, God Save the Queen/My Country 'tis of Thee, Jingle Bells, Twist and Shout/La Bamba, Auld Lang Syne ...
There are even some pieces of music which only use two chords - see if you can play along while you sing Jambalaya, He's Got the Whole World in His Hands, or even Mozart's Horn Concerto (yes, really!), just using the chords C and G.
When songwriters or composers use the three chord trick, or even just the I and V chords, they are using a fundamental principle of music, known as tension and resolution. Think of the familiar rhythm and melody snippet Shave and a haircut - two bits. You can accompany this with the chords C and G as follows:
C G C
Shave and a haircut ... two bits
The harmonic structure of this phrase is I V I. If we shortened it to just the I chord, or the words Shave and a haircut, it would sound rather dull and unsatisfying, because there is no movement in the harmony. Now try extending it to the words Shave and a haircut - two, which includes the V chord, G. This sounds more interesting, because the harmony has moved from I to V - however, it also sounds even less satisfying than the first version - it seems to be hanging in mid-air, unfinished. This is because it has not returned to the tonic chord, C. When we listen to music, we are usually aware that it has a specific key centre, even if we do not know which key it is in. Our minds expect the music to return to the tonic of that key at the end of the piece, so that it sounds complete, or 'resolved'. The V chord is described by musicians as being 'tense'. The tension it produces gives a strong psychological 'pull' towards the I chord. (Note that the chord of G major is not tense in itself - it only sounds tense in the context of a piece of music in C major.) When we complete the phrase with the C (or I) chord on the word 'bits', our harmony is resolved and it sounds complete and finished. The same thing applies to 'Roll Over Beethoven' as it resolves from the V chord on 'over', via the IV chord on 'hear', to the I chord on the final syllable 'day'.
This principle of tension and resolution is common to nearly all western music, and there are many very complex and sophisticated ways of using it - we have just looked at some very simple cases.
If you've never done so before, I recommend that you spend some time working out some three chord trick songs. Start with anything you know from the list above, then think about pop songs you hear on the radio, folk tunes, whatever. You might be surprised by how many songs rely on this simple formula.
In Part Three, we will look at how songwriters and composers use some of the other chords from the diatonic series.