Music Theory - Diatonic Chord Progressions
This lesson is intended to give a basic understanding of harmonic function related to a major key, designed to analyze and create chord progressions. Examples are given in the key of C Major.
Contents
PreReqs
Diatonic Chords
Chords are considered diatonic to a particular key if they only contain notes found inside that key. The major scale has 7 distinct notes, giving us 7 possible choices for the roots of diatonic chords. Using the 3rds and 5ths of each root that are also found inside the key gives each chord a particular quality. In a major key, there are 3 major, 3 minor, and 1 diminished diatonic chords.
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Note that simply because the root of a chord is in the scale doesn't mean that any chord with that root is diatonic to the key. Gm, A, and Bm all have roots in C Major but are not diatonic to C Major. Gm has a B♭, A has a C♯, and Bm has a F♯. B♭, C♯, and F♯ are not found in the key of C Major.
Let's compare C Major to G Major, which has the exact same notes as C Major except an F♯ instead of F. Changing that one note (F -> F♯) affects 3 of the chords. B° becomes Bm (d5 -> P5), Dm becomes D (m3 -> M3), and F becomes F° (the raised root changes both intervals: M3 -> m3, P5 -> d5). Notice that G, Am, C, and Em are diatonic to both C Major and G Major, as none of these chords contain F or F♯.
Harmonic Functions
At the most basic level of abstraction, each diatonic chord has one of three harmonic 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 away from tonic chords and into dominant chords. Here is a table with all the diatonic chords and their function for C Major:
| Chord in C Major | Harmonic Context | Name | Parallel of | Harmonic Function |
|---|---|---|---|---|
| C | I | Tonic | Tonic | |
| Dm | ii | Supertonic | IV | Pre-Dominant |
| Em | iii | Mediant | V | Tonic/Dominant |
| F | IV | Subdominant | Pre-Dominant | |
| G | V | Dominant | Dominant | |
| Am | vi | Submediant | I | Pre-Dominant/Tonic |
| B° | vii° | Leading | Dominant |
Notice the I, IV, and V chords are the only ones with unambiguous functionality (except B° which is covered later. Ordering those chords by harmonic functions gives us our first and most basic chord progression: I - IV - V - I:
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:
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--------------------------
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?
So if all these chords fall into these functions and each one leads into the next one, how do we create unique compositions? It may feel like these rules are locking us inside a cage where we can make a substitution here and there but aren't really free to branch out. Here are several points to keep in mind:
- We are omitting one of the diatonic chords - the vii°.
- We are only using diatonic chords.
- We are immediately moving from one function to the next, rather than hanging around and embellishing the function before moving on.
- We are confined to one key instead of modulating or borrowing from other keys.
- We haven't entertained the idea that we can ignore the functions described above, or that other contrary functions may exist.
- We are only looking at harmony, without any context of melody or rhythm. Even with all the points above, a seemingly simple progression can undertone a wide range of actual songs. Check out the 4 chord song by Axis of Awesome.
Circle Progression
Another way to progress through chords is given to us by the circle of fifths. We haven't covered that yet, but we will soon. Essentially, it arranges notes in order of fifths, with each note being a perfect fifth higher than the previous note. Here's the notes from C♭ to C♯ along the circle of fifths.
|------------------------------------------------| Cb - Gb - Db - Ab - Eb - Bb - F - C - G - D - A - E - B - F# - C#
Enharmonically, G♭ and F♯ are the same pitch (as are C♭ and B); so the circle is just repeating at that point, indicated by the range above the notes above.
If we use only diatonic notes for any particular major key, the 7th note does not have a perfect fifth but a diminished fifth. In C Major, B-F is a diminished fifth instead of a perfect fifth; however, we can still make the circle by using diatonic 5ths, substituting in the d5 as appropriate. This makes the "circle" smaller:
|-----------------------| F - C - G - D - A - E - B - F - C
We have already learned that the strongest harmonic resolution is from Dominant to Tonic (or V - I). The circle progression makes use of this - we simply traverse the circle backwards, so that the root note of the next chord is a 5th below (or inversely a 4th above) the current one. So in the key of C Major, a complete circle progression is:
C - F - B° - Em - Am - Dm - G - C I - IV - vii° - iii - vi - ii - V - I
We haven't talked about that B° (B Diminished) chord yet, so let's leave it out. This leaves us with:
C F Em Am Dm G C I IV iii vi ii V I E-0---1---0---0---1---3---0-- B-1---1---0---1---3---3---1-- G-0---2---0---2---2---0---0-- D-2---3---2---2---0---0---2-- A-3-------2---0-------2---3-- E---------0-----------3------
Every chord leads into the next pretty seamlessly. Notice we basically have 2 passes through the tonic - subdominant - dominant - tonic paradigm of harmonic function. I-IV-iii-vi and vi-ii-V-I.
The circle progression gives us a basic roadmap of how to get from any chord to any other chord in the same key. Knowing harmonic function allows us to take "shortcuts" and jump some intermediate chords. For example, we know the harmonic function of IV is pre-dominant, so we can jump from IV to any dominant function chord. Let's choose V. That leaves us with I - IV ... - V - I. We're back to our basic I - IV - V - I example!
Sample Progression
Let's make up a song real quick. We will use the key of C Major (do we have a choice yet?) and want to start on the tonic. Let's add some rhythmic variety. We'll stay on the C major chord for a full measure, which will help really establish the key of C Major. Then let's repeat the part of the circle progression again from iii to ii. We know that ii is a predominant function and iii can have a dominant (as well as tonic) function, so let's dwell on the ii for an extra beat, then go back to iii. From iii we circle progress again, but instead of stopping at ii, this time we'll keep going to V.
C Em Am Dm Em Am Dm G C I iii vi ii iii vi ii V I E-0-------------|-0---0---1------|-0---0---1---3-|-0---------- B-1-------------|-0---1---3------|-0---1---3---3-|-1---------- G-0-------------|-0---2---2------|-0---2---2---0-|-0---------- D-2-------------|-2---2---0------|-2---2---0---0-|-2---------- A-3-------------|-2---0----------|-2---0-------2-|-3---------- E---------------|-0--------------|-0-----------3-|------------
Play this nice and slow. You don't want to be jumping from chord to chord very quickly - it ruins the harmonic impact. Start at like 50 bpm. Most chord progressions dwell on each chord for a full measure. But without drums and a melody, that's a bit boring.
Bad Examples
Let's be bad and break the rules, just to see what happens...
C Dm Am Em F Am G Dm C G I ii vi iii IV vi V ii I V E-0-------------|-1---0---0------|-1---0---3---1---|-0------3------- B-1-------------|-3---1---0------|-1---1---3---3---|-1------3------- G-0-------------|-2---2---0------|-2---2---0---2---|-0------0------- D-2-------------|-0---2---2------|-3---2---0---0---|-2------0------- A-3-------------|-----0---2------|-----0---2-------|-3------2------- E---------------|---------0------|---------3-------|--------3-------
Here's the same example as above, but I've changed the order of a few chords, added the IV into the mix, and added a V as the last chord. Let's analyze what's going on.
Instead of the iii - vi - ii progression, we have the reverse. This is opposite the circle progression and should seem to slightly increase tension, but overall, it's not too bad. The chords ii and vi chords serve a predominant function, whereas the iii can serve as dominant.
The next measure is a bit crazier. We go from the held dominant-function iii to IV, the staple pre-dominant chord. This transition should be a bit odd. Then we move to the vi, which also has a predominant function, but is a bit weaker than the IV in this regard. In this respect it appears we are moving away from predominant and towards tonic (iii and vi have some tonic functionality). But then we go to the V chord, which is a bit unexpected and contrary to the last chord. From V, we go back to ii. This is a poor resolution - the tension already built should continue or even heighten.
From ii we go back to I. This is a very poor resolution, especially to the tonic. Much of the tension created will not be relieved, and even though we've reached the tonic chord, we won't feel like we've completed our musical journey. And then we progress to a final V chord. Remember that the dominant chord has the most tension to resolve to tonic. We never resolve it...
As bad as that example was, it's not that bad. Since all diatonic chords fit into one of 3 basic functions and the functions merely describe the interrelated tension, most progressions that exclusively use diatonic progressions and begin and end on the tonic should sound relatively good. Also, remember that tension itself is not bad. In fact it's good to keep things from being boring. Let's see about that:
C Am Em Em Am C I vi iii iii vi I E-0-------------|-0-------0------|-0-------0------|-0---------- B-1-------------|-1-------0------|-0-------1------|-1---------- G-0-------------|-2-------0------|-0-------2------|-0---------- D-2-------------|-2-------2------|-2-------2------|-2---------- A-3-------------|-0-------2------|-2-------0------|-3---------- E---------------|---------0------|-0--------------|------------
This progression uses only chords with some tonic functionality. And we begin and end on the tonic chord. We avoid any dominant to tonic resolution which could occur between iii and I. Is this progression wrong? No - it doesn't break any rules so to speak. It just doesn't have any strong tension or release. This can be desirable or not given the circumstances.
Well, how about a truly bad example then...
C Dm Em F G Am C I ii iii IV V vi I E-0------1------|-0------1-----|-3-------0------|-0---------- B-1------3------|-0------1-----|-3-------1------|-1---------- G-0------2------|-0------2-----|-0-------2------|-0---------- D-2------0------|-2------3-----|-0-------2------|-2---------- A-3-------------|-2------------|-2-------0------|-3---------- E---------------|-0------------|-3--------------|------------
Here, we are simply ascending the C Major scale, with each note used as the root of the next chord in the sequence: C Dm Em F G Am. ii has a predominant function, so it's no so bad that it leads into iii, but this implies the iii has a dominant function. The next chord is IV, the main pre-dominant chord. iii - IV might work if the iii has a tonic function, but in this case it doesn't; and the transition will sound awkward. IV - V is common and worry-free progression, but the following V - vi hurts the dominant functionality of the V. Even though vi can have tonic functionality, it is much less strong than the V - I, dominant - tonic resolution. Then we have vi - I. The vi likely serves a tonic functionality here, coming off the preceding V. This makes the vi - I progression weak and uneventful, probably the opposite of what is desired leading into the last chord of the piece.
Again, is this example 100% terrible? Not really. Since we are using only chords diatonic to C Major, the tonality is still grounded and evident, which is enhanced by starting and ending on the C major chord. We have mucked up harmonic function, but we haven't destroyed tonality. A truly, absolutely terrible example, would basically feature random chords from various keys, seemingly having no tonality or direction.
Cadences
Cadences are harmonic devices to create a sense of resolution for the end of a progression. There are several types, based on the chords involved, as well as their voicing.
Authentic Cadence
An Authentic Cadence is a dominant-tonic progression. The dominant 7th (covered later) can be used in place of the dominant triad. A perfect authentic cadence must use the V or V7 chord as the dominant, have both chords in root position, and voice the tonic note in the tonic chord in the highest voice. An imperfect authentic cadence is similar, but breaks one or more of the above conditions. It may substitute the vii° chord for the V.
Half Cadence
A Half Cadence is a progression that moves from basically any chord to the V chord, leaving a sense of unresolved tension. The cadence is still designed to indicate the end of a phrase or musical idea, but it begs for continuation, either through a repetition or another idea/section.
Plagal Cadence
A Plagal Cadence is a IV - I progression, also called the "Amen Cadence" because of its frequent use in church hymns. Because there is no leading tone to tonic movement, the cadence does not imply tonality. For instance a I-IV-I progression could also be interpreted as a V-I-V progression. In this way, it is a weak resolution, but a resolution to tonic, nonetheless.
Interrupted/Deceptive Cadence
An interrupted or deceptive cadence is a V-vi or V-VI progression, commonly using V7. This creates a weak or suspended feeling, similar to the half cadence.
Homework
- Memorize the tables of chords and functions above - you should already be familiar with most of it from past lessons, but try to get it fully memorized now.
- Play through all the progressions on this page, following the analysis of harmonic function or how it relates to the circle progression.
- Create at least 3 of your own progressions. Learn how to establish the key of C Major, create tension, and relieve it.
Congratulations - you are ready to move on to Intermediate Lessons!!!!