Dominant 7th major open chords
Dominant 7th chord formations are a little different. The principles are still the same as a standard major chord formation but the 7th note is added in. The 7th note played in a dominant 7th chord will be lowered ½ step. If a C major scale is: C D E F G A B C, Root = C, 3rd = E, 5th = G, and 7th = Bb. The formula for this chord formation is R-3-5-7. If we have a four note construct, a triad will still be the basic form in notation with an additional tone, the 7th. This is incredibly useful information as there are several larger chords that are used frequently in music.
Here are some of the common ways that these chords and notes will be referred to. C7, D7, E7, F7, G7, A7, B7, Cdom7, Ddom7, Edom7, Fdom7, Gdom7, Adom7, Bdom7. Dom = Dominant