Extended chords - 7th chords

Extended chords are usually built by added a series of 3rds on top of the triad.

A 7th chord is called an “extension” b/c you are adding additional notes to the 1-3-5 notes that compose a common triad. As the name indicates, we are adding the 7th note of the scale, so the chord has 4 notes, not 3.


Types of 7 chords
There are 4 types of 7 chords that you need to know. Here are those 4 types and their formulas:
Major 7th chords: 1,3,5,7
7 chords :   1,3,5,b7  (sometimes called dominant 7th chords, but that will be discussed in a later lesson)
Minor 7th chords:  1, b3, 5, b7
Half Diminished 7: 1, b3, b5, b7
These 7 chords are built the same way that triads are built—by stacking 3rds. Lets take a look at some of these chords by using notes from the C major scale
C - D – E – F – G – A – B
Now lets build a Cmaj7 chord. To do that we will start stacking 3rds from the C note. So we have C,E,G,B, or 1,3,5,7. So Cmaj7 chord is spelled C,E,G,B. At the end of this lesson will have chord charts for how to play this chord on guitar.
Now lets build some more chords. Here are the 7 chords for D through B. In the prentices I will put that chords major scale so you can compare the notes with the formula used to derive the 7 chord.
ii Dm7 – D, F, A, C (1,b3,5,b7 of D major: D, E, F#, G, A, B, C#, D)
iii Em7 – E, G, B, D (1,b3,5,b7 of E major: E, F#, G#, A, B, C#, D#, E)
IV Fmaj7 – F, A, C, E (1,3,5,7 of F major: F, G, A, Bb, C, D, E, F)
V G7 – G, B, D, F (1, 3, 5, b7 of G major: G, A, B, C, D, E, F#, G)
vi Am7 – A, C, E, G (1,b3,5,b7 of A major: A, B, C#, D, E, F#, G#, A)
viiº Bm7b5 (AKA B half diminished) – B, D, F, A (1,b3,b5,b7 of B major: B, C#, D#, E, F#, G#, A#, B)
Here is a look at the easiest way to play these 7th chords on guitar. Note that there are MANY other way to play these 7 chords on guitar: