Music Theory - Diatonic Chord Progressions

This lesson is intended to give a basic understanding of harmonic function related to a major key.

Harmonic Functions

At the most basic level of abstraction, each diatonic chord has one of three functions: tonic, pre-dominant, or dominant. The function of tonic chords is to establish tonality or resolve tension. Thus it is often the first and/or last chord in a song. Dominant functions to create tension that can be relieved by tonic chords. Pre-dominant chords serves to lead into dominant chords.

This gives us our first and most basic chord progression: I - IV - V - I:

fig 1
   C    F/C    G/B    C
   I    IV      V     I
e--0-----1------3-----0----
b--1-----1------0-----1----
g--0-----2------0-----0----
d--2-----3------0-----2----
a--3-----3------2-----3----
e--------------------------

Ok, yeah, so we already saw this in a prior lesson. Well let's switch some chords to parallels with the same harmonic function:

fig 2
   Am   Dm/A   G/B    C
   vi    ii     V     I
e--0-----1------3-----0----
b--1-----3------0-----1----
g--2-----2------0-----0----
d--2-----0------0-----2----
a--0-----0------2-----3----
e--------------------------

fig 3
   Am    F/A   Em/B   C
   vi    IV    iii    I
e--0-----1------0-----0----
b--1-----1------0-----1----
g--2-----2------0-----0----
d--2-----3------2-----2----
a--0-----0------2-----3----
e--------------------------

Those are a bit different, but they all seem to "push" in the same direction, right?