Chord Function
Chord function describes the role a chord plays in a key. There are three primary functions: tonic (home, stability), dominant (tension, urgency), and subdominant (movement, departure). Almost all harmonic motion is organized around these three roles.
The Three Functions
| Function | Degrees | Feeling |
|---|---|---|
| Tonic | I (also iii, vi) | Stability, home, resolution |
| Dominant | V (also vii°) | Tension, urgency, need to resolve |
| Subdominant | IV (also ii) | Movement, departure, transition |
How Functions Drive Music
The tonic is harmonic "home." When you hear a I chord at the end of a phrase, you feel resolution. The dominant creates the strongest tension — the V7 chord contains a tritone that desperately wants to resolve to I. In C major, G7 (G-B-D-F) has a B-F tritone that "wants" to become C-E. This V-to-I resolution is the most fundamental cadence in Western music.
The subdominant provides movement without the dramatic tension of the dominant. It can lead to the dominant (IV-V-I) or resolve directly home (IV-I, called the "amen cadence" because of its use in hymns). The ii chord is a subdominant substitute preferred in jazz because ii-V-I flows more smoothly than IV-V-I.
Common Functional Progressions
I-IV-V-I (departure-tension-home): the most basic complete progression. ii-V-I (departure-tension-home): the fundamental jazz cadence. I-V-vi-IV (home-tension-emotional-departure): the modern pop progression used in hundreds of hit songs.
In Chord8
Chord function is implicit in the KEY row's Roman numerals. The 12 progression routes demonstrate these functional movements in action and can be opened directly to hear tonic, dominant, and subdominant interact.