Useful Music Theory Part 2: Forming Diatonic Chords

author: UtBDan date: 08/23/2012 category: chords
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Useful Music Theory Part 2: Forming Diatonic Chords
So hopefully we all have a firm grasp on how to name intervals and how to form the major scale after reading Part 1. To recap, the major scale is composed of the Root, and its Major 2nd, Major 3rd, Perfect 4th, Perfect 5th, Major 6th, Major 7th, and its Perfect Octave or 8th. To start the next lesson, we must know what a chord is, and what a triad is, and what's the difference. We should also know what the term diatonic means. A triad is any three different notes played at the same time. A chord is any three OR MORE different notes played at the same time. For this reason, the term "power chord" is actually a misnomer: a power chord is a Root and a 5th, and that is only two notes. But hey, it certainly is powerful. If you don't know the term diatonic, don't look it up. A dictionary is going to give you a complex definition that ultimately means the following: within or pertaining to the major scale or its modes. So what is forming diatonic chords? Diatonic chords are forming chords based on the major scale! Simple as that. A diatonic triad is typically made of a Root, a third, and a fifth. This could also be viewed as going up a third and then another third within the scale. That might sound a bit confusing, but look at this way: going up a third from the Root lands on the third note of the scale. Going up a third from the third note of the scale lands on the fifth note of the scale. The four types of diatonic triads (one of these will only come up much later in the minor scales, so don't fret too much) are the following: 1. A Major chord: a Root, its Major 3rd, and its Perfect 5th (or: A note, go up a Major third, then go up a minor 3rd.) 2. A minor chord: a Root, its minor 3rd, and its Perfect 5th (or: A note, go up a mior third, then go up another major 3rd.) 3. An augmented chord: a Root, its Major third, and its Augmented 5th (or: A note, go up a Major third, then go up another Major 3rd.) 4. A diminished triad: a Root, its minor third, and its diminished 5th (or: A note, its minor third, then go up another minor 3rd.) Going back to the idea of stacking thirds within the scale to get the chords within the scale, the first chord of a major scale is... A Major chord. Not exactly shocking. To use C major (C D E F G A B C) as an example, we can watch our defintition of the C major chord/triad match up with the C major scale. C D E F G A B. Root, third, fifth. That wasn't too tricky. The part a lot of people get lost at is the other chords diatonically. For example, the triad based on the root of the major scale is always a Major triad or Major chord. But what about the second chord? The chord based on the second note of the major scale is always a minor triad or chord. If we know a minor chord is a Root, minor third, and perfect fifth, we know a D minor chord is D, F, A. Now let's look at the C major scale again: C D E F G A B This will always be the case in major scales and its second note. I could do this individually with each triad on the entire scale, but it'll be easier to just show you what all the chords turn out to be. For the uninitated, people use numbers in reference to music theory when referring to intervals (Major 5th), and Roman numerals when referring to chords (a V chord). Typically with chords, upper case roman numerals mean major chords, and lower case mean minor chords. The degree sign () means a diminished triad. As such:
  • The chord based on the Root of the major scale is always Major, It is often called I.
  • The chord based on the second note of the major scale is always minor. It is often called ii.
  • The chord based on the third note of the major scale is always minor. It is often called iii.
  • The chord based on the fourth note of the major scale is always major. It is often called IV.
  • The chord based on the fifth note of the major scale is always major. It is often called V.
  • The chord based on the sixth note of the major scale is always minor. It is often called vi.
  • The chord based on the seventh note of the major scale is always diminished. It is often called vii. If you understand that, you can go one step further, and add sevenths. Keep stacking things, and just as every kind of triad was a root, a third, and a fifth, every seventh chord is a root, a third, a fifth, and a seventh. There are a few types of seventh chords you'll need to know: 1. A Major 7th chord: A Root, its Major 3rd, Perfect 5th, and Major 7th (or: A note, then go up a major third, then go up a minor third, then go up a major third.) In rock/jazz music, is it was shortened as a maj7 chord. 2. A minor 7th chord: A Root, its minor 3rd, Perfect 5th, and minor 7th (or: A note, then go up a minor third, then go up a major third, then go up a minor third.) In rock/jazz music, it is shortened as a m7 chord. 3. A Dominant 7th chord: A Root, its Major 3rd, Perfect 5th, and minor 7th (or: A note, then go up a major third, then go up a minor third, then go up a minor third.) In rock/jazz music, is it shortened simply as a 7 chord. 4. A half diminished 7th chord: A Root, its minor 3rd, diminished 5th, and minor 7th (or: A note, then go up a minor third, then go up a minor third, then go up a major third.) In rock/jazz music, it is shortened as a 7 chord (or, somewhat predictably, a m7b5. This is because it is a minor 7th chord with a flatted fifth.) 5. A fully diminished 7th chord: A Root, its minor 3rd, diminished 5th, and diminished 7th (or, my favorite: A note, then a minor third, then another minor third, then another minor third.) In rock/jazz music, it is shortened as a 7 chord. Applying this to the major scale (and going back to roman numerals), we learn that the diatonic chords are: My examples will always be in C major, because it keeps things the simplest to see. Imaj7 (C D E F G A B) iim7 (D E F G A B C) iiim7 (E F G A B C D) IVmaj7 (F G A B C D E) V7 (G A B C D E F) vim7 (A B C D E F G) vii7 (B C D E F G A) And those are your diatonic chords! There are many other chords out there, but those are the standard ones built on triads on the major scale. Feel free to ask any questions in the comments. Part 3: The Three Minor Scales will be coming soon, as well as more in this series.
  • More UtBDan lessons:
    + Useful Music Theory Part 3: The Three Minor Scales Scales 09/03/2012
    + Useful Music Theory Part 1: The Major Scale And Intervals And Getting A Basis For All Future Music Theory Scales 08/20/2012
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