Originally Posted by: WeslabaSo... is there any way the 7th's fit into the major minor minor major major minor diminished pattern? Such as 7 m7 m7 maj7 maj7 m7 ... ? :confused:

Applying notes to the pattern might help. Keeping with the G Major scale for an example, the pattern would be;
G Major = G-B-D
A minor = A-C-E
B minor = B-D-F#
C Major = C-E-G
D Major = D-F#-A
E minor = E-G-B
F#m/b5 = F#-A-C

When you see 7 added to a chord, this note is referenced to the m7th (b7) interval from the Root note of that chord. Just because it's noted as the minor 7th interval doesn't necessarily mean that it's a minor 7th chord; The 3rd interval dictates the chord's Major or minor status. If a b3rd follows the Root note of a chord, it's minor, if it's a 3rd (up 2 Whole steps), it's Major.
The 7th note title will be located 2 semitones (1 Whole step) lower than the Root note. Example; The m7th note title from Root "A" would be "G".

For a chord to add a M7 interval from it's Root, it's referenced as a maj7 chord. Again, this dictates the M7th interval, not the Chord's status.
For a maj7 chord to fit the Key, the M7's (Leading note) title must be located one semitone (1/2 step) lower than the Root note of that Chord. Example;
The M7 title from "G" would be "F#".
Now Down to business adding the 7th to the above chords;
Gmaj7 = G-B-D-F#
Am7 = A-C-E-G
Bm7 = B-D-F#-A
Cmaj7 = C-E-G-B (B is one semitone lower from C)
D7 = D-F#-A-C (this is a D Major Chord, Referred to as a Dominant 7th chord)
Em7 = E-G-B-D
F#m7/b5 = F#-A-C-E (This Chord is Referred to as "F# Half Diminished")

Many players claim not to pay much attention in learning the diminished chords/scales because they rarely get used, so practicing the F# Locrian mode is a waste of time......... I beg to differ and encourage everyone to implement them in their playing. Remember the reference to "Leading note" because the chords and improvs that integrate them are strong to emphasize the Tonal Center. In the Key of G the Leading note is F#. The D7 chord takes it even one step further; it's 3rd is F# and the b7th is C, which creates a Tritone and begs for resolve to the Tonic.
Play a D7, then a F# Half Dim chord (F#m7/b5... The Half Diminished chord has the intervals 1-b3-b5-b7, noted sometimes as F# HD) and see how closely they relate in substitution.
There are five qualities of the 7th chord (in Western music);
1) maj7
2) dom7
3) m7
4) Half Diminished
5) Diminished 7 (Symmetric qualities)

Here's how they relate to each other by one interval change.

__7>>>>>>b7_________b7______b7>>>>>>>>bb7 (6th)
__5________5_________5>>>>>>b5__________b5
__3________3>>>>>>>b3______b3__________b3
__1________1_________1_______1___________1
maj7........dom7............m7.........hd..............dim7

Next post, I'll show how closely related these 7th chords are.