G Major Key Signature

Changing from the key of C to the key of G means a change in the key signature. Once the key signature is figured out, then we can look at the notes in the G Major scale and the different chords built upon each degree of the scale.

In the key of C, there are not any sharps or flats in the key signature.
G is a fifth above C and is the fifth note in the key of C.
When changing from one key to another key that is a fifth above, a single sharp is added to the key signature. This sharp is added to the 7th note of the new key.

So changing from the key of C with no sharps or flats to the key of G which is a fifth above C, a single sharp will be added to the key signature. This sharp is F#. F is the seventh note in the key of G and so will be raised to F#.

The key of G has a key signature with a single sharp, F#.

So the notes in the key of G are G, A, B, C, D, E, and F#.

Guitar Chords in G

The chord built upon the first note of a major scale is a major chord. In this case G Major. The notes that make up G major are G, B, and D

The chord built upon the second note of a major scale is a minor chord. Here we have A minor made up of the notes A, C, and E

The chord built upon the third note of a major scale is another minor chord. The iii minor chord in G is B minor. The notes in B minor are B, D, and F#.

Building a chord on the fourth note of a major scale results in a major chord. In the key of G, the IV chord is C major. C major is made up of the notes C, E, and G.

The V chord in the key of G is D. D Major consists of D, F#, and A. Extending that to a dominant 7th chord results in D7: D, F#, A, and C.

The vi minor chord in the key of G is E minor which is made up of the notes E, G, and B.

Finally, the chord built upon the seventh note of a major scale is diminished and in this case is F# dim which consists of the notes F#, A, and C.