Chord Function - I

Basic theory

The key note, or tonic, of a piece of music is called note number one, the first step of (here), the ascending scale iii–IV–V. Chords built on several scale degrees are numbered likewise. Thus the chord progression E minor–F–G can be described as three–four–five, (or iii–IV–V).

A chord may be built upon any note of a musical scale. Therefore, a seven-note diatonic scale allows seven basic diatonic triads, each degree of the scale becoming the root of its own chord.

Audio Example

A IV–V–I progression in the key of C major (example audio).

Common progressions

Simple progressions

Diatonic scales such as the major and minor scales lend themselves particularly well to the construction of common chords because they contain many perfect fifths.