Scales and Chords

Can someone explain the theory behing matching specific chords with the steps of a scale? I heard that for every scale there are a group of chords that are compatible or match.

What up, holmes.

Here are some of the basics -

Ionian - major, maj7
Dorian - minor, min7
Phrygian - minor, min7
Lydian - major, maj7
Mixolydian - major, 7th
Aeolian - minor, min7
Locrian - dim5, min7thb5

There are, of course, more . . . you just have to figure out what fits in the key signature.

I have all that, but what is the purpose, or how does it all apply?

Well whenever you come accrosst a certain chord, those are the scales you can pick from to play over that chord. i.e. Say you see a Bm7b5 chord, well just play a B locrian mode over it. And if you understand how modes exist within the major scales, you can see what chords work within a certain major scale (key signature) i.e. "I" is Ionian, so "II" is Dorian, and so on. So if you have a tune in the key of E major, E is the "I" (Ionian), F# would be "II" (Dorian). So in the key of E major, F# could be played as a minor 7th chord and the F# Dorian is good scale to play over that chord.

I would refer to your basic pattern of sharps and flats. Every key will have different notes that can be used. Once you find out what notes a key uses, you can make a triad chart to find chords that will fit in with those notes.

It's worth mentioning that if you extend a chord far enough your expression will include all the notes of a given scale, so a 13th chord expresses all 7 notes of a particular scale.

Originally posted by u10ajf
It's worth mentioning that if you extend a chord far enough your expression will include all the notes of a given scale, so a 13th chord expresses all 7 notes of a particular scale.

Although on the guitar it's impossible to play all 7 notes on a 6 stringer. Usually one or more notes will be excluded, just as long as the 3rd, 7th, and 13th are there. Another thing is when a 13th chord is heard; the minor 13th matches with the (root) minor scale, the major 13th matches with the (root) major scale, and the dominant 13th matches with the mixolydian mode. You won't hear a truly natural 13th chord on any other chordal tone. If so it's most likely a dominant 13th in a cycle 5th. Keyboardists tend to use them alot.