[Gil]

I have been playing for many years but finally decided to study theory. This a great site. As I was watching the video on how to know which chords go in each key, I was really thrown when the instructor said that the seventh chord in a scale was a diminished chord. Exactly what is a diminished chord and how do you construct one without looking at a chord chart?

If the 7th chord of the scale is diminished, why isn't more emphasis put on it and why isn't it used more often?

One other question, and I am not sure if it is related or not; In an old Dylan song called It takes a lot to laugh, it takes a train to cry, it is in the key of G. It goes from G to C to G to C and so on then to D and return to the G-C progression. Then when it goes to F then G. The F is not a diminished chord, why does it work here.

I am sure this is a very basic question but I really want to understand how to arrange music. It seems like there are many chords that are out of key but still fit. What is that? How do you know which of the chords that are out of the key will fit?

Thanks so much for the help.

[tybacca60]

Lol,im not too much of a theory guy,but im sure some1 will help you here in a bit.

[MatthiasYoung]

Just because a chord is not in the same key doesn't mean that it will sound bad. On the contrary, borrowing a chord from another key can add a lot, provided it is done correctly. One reason why the diminished vii chord is not used that much, is that if you add the 5th scale degree underneath, you get a Dominant 7th chord, which creates a strong cadence. To keep it simple, take the key of C. A viidim would be spelled B D F. If we add the G to the chord, we get a G7 chord.

And since we're talking about theory, the vii chord and a 7th chord are not the same thing. A 7th chord has a root, third, fifth, and seventh. This can be any scale degree. A vii chord only has three notes, but the root is the seventh scale degree.