Guitar chords in the key of C major:
Chord C7 (5th fret) v.2 notes: C, E, G, C, E and Bb.
This chord is played by placing a barre on fret five with your index finger.
C dominant 7th chord's alternative names: Cdom7, (C septim).
1(C), 3(E), 5(G), b7(A#/Bb).