Is a Cm7 chord considered minor or dominant? I'm studying jazz and trying to identify chord scales for particular harmonies. Also, what modes qualify to possibly fit with a Cm7 chord and how do I determine which they are?
The question whether Cm7 can be considered a dominant chord has already been answered (the answer is: no). But now for the chord scales. Any scale containing a Cm7 chord can function as a chord scale for Cm7:
- C dorian: C D Eb F G A Bb
- C aeolian: C D Eb F G Ab Bb
- C phrygian: C Db Eb F G Ab Bb
The difference is the number of avoid notes that these scales have (with respect to the Cm7 chord). Dorian has none, aeolian has one (the sixth scale degree Ab), and phrygian has two avoid notes (the second and the sixth degrees, Db and Ab). Avoid notes are, loosely speaking, scale notes that are a semitone higher than a chord tone. The fact that the dorian scale has no avoid notes when used over a minor seventh chord makes it the most used chord scale for such a chord.
For more information about avoid notes take a look at this blog post.
It's definitely not dominant because you don't have a diminished triad between the 3rd, 5th, and 7th so it can't function as dominant. If you break it up, you actually get a minor triad between the root, 3rd, and 5th and a major triad between the 3rd, 5th, and 7th.
It is just a minor 7th found in a few different scales/modes pretty much any natural mode that is minor. A basic dominant chord chord would typically contain a root, major third, perfect fifth, and minor seven as shown here.
There's THE dominant of a key, which is the fifth note of the home scale, or the chord built on it. Or there's a more loosely-defined dominant function which can consider Am7, Dm7, G7, C as a string of "secondary dominants". You can spice this up by making the secondary dominant chords major - A7, D7, G7, C is quite normal and acceptable, and if your theory book can't cope with it without inventing temporary modulations or "borrowing" chords, get a better theory book! Much jazz is based on jumping to a remote chord and finding the way home through a string of secondary dominants, or their b5 substitutions. Even "Giant Steps" is largely a series of ii7, V7, I fragments. This "string of dominants" is such a strong progression!