C Major scale harmonized in chords
I II III IV V VI VII
C maj, D min, E min, F maj, G 7, Am, Bdim
I think this is pretty much standard, as I've seen this before, though perhaps with different notation (lowercase i for the minors, like this: I ii iii IV V vi vii*).
So the chords are basically made up of the 1,3, and 5 notes, like so:
Cmaj = C E G
Dmin = D F A
Emin = E G B, etc.
OK, I understand that the ii, iii, and vi are minor because the 1-3-5 is made up of the root, a minor third (3 semitones from the root), and a perfect fifth (7 semitones).
I understand why the IV and V are major because their 1-3-5 are the root, the major third, and the perfect fifth.
The one I don't get is the vii. This should be made up of B D F, in the key of C. In this case it's referred to as Bdim.
When I looked up Bdim in a chord book I found this
This chord has is made up of B, F, G#, and D.
The G# is not part of the C scale and harmonically, doesn't seem to fit. I tried to search for chords with just the B, F, and D on chordbook.com and it couldn't identify it. I should also note that trying to make a chord with the B F and D in anything besides the open position is a bit of a bitch.
Is the diminshed chord the correct chord for the vii?