7ths and 5ths and 6ths and chords oh my!

[zbalz]

I recently got the complete guitarist book and I've been reading up on it recently. They mention in there that for chord progressions, there are primary movements in a major scale. I major, II minor, III minor, IV major, V maj/dominant 7th, VI minor, and VII Diminished. I was just wondering why II, III, and VI are minors and such. Is it because it sounds good when someone is soloing in that scale? If that is the reason, is there any theoretical reason for it "sounding good"?

They also mention a bit about sevenths (when having to do with chords). They say major 7ths are at I and IV. Dominant sevenths are at V only. Minor 7ths are at II, III, and VI. and diminished 7ths are at the VII. Obviously this has much to do with the movements I mentioned above but what IS the relation?

Thanks

-zbalz

[StoneDragon]

This is what is commonly known as harmonizing the scale. I usually refer to it as the chord scale.

Take a look at my chord scale lesson (http://www.zentao.com/guitar/theory/chord-scale.html) in the theory section. You'll see that each of those chords are formed by using only notes found from within the major scale.

If you add the 7th interval to each chord in the chord scale (still using only notes found in the major scale) you will arrive at the 7th chord variations. Check out the7th chords lesson (http://www.zentao.com/guitar/theory/7th-chords.html) also in the theory section.

[zbalz]

Thanks. I didnt realize you had a lesson on that. You always seem to have a better way of explaining things compared to other places http://www.zentao.com/ubb/smilies/smile.gif

-zbalz