Seventh Chords

The name gives it away: seventh chords chords must have some kind of seventh in them. Indeed, they are triads bringing their plus-one. Here are some examples with root GG:

X:1 L:1/4 K: C "GΔ"[GBd^f] | "Gm7"[G_Bdf] | "G7"[GBdf] | "Go7"[G_B_d_f] | "Gø"[G_B_df] ||
Sheet MusicGm7G7G°7

The first of these examples, the GG^\triangle is a G major 7. In this chord symbol, GG signifies that the base triad is G major, and the \triangle specifies the character of the seventh -- this one is a major seventh, as opposed to a minor seventh. Read 1-intervals{.interpreted-text role="doc"} first if you don't know what this means. Here are three examples of major seventh chords:

G={g,b,dundefinedG major triad+fundefinedmajor seventh}D={d,f,aundefinedD major triad+cundefinedmajor seventh}B={b,d,fundefinedB major triad+aundefinedmajor seventh}\begin{aligned} G^\triangle &= \left\{ \underbrace{g, b, d}_{G \text{ major triad}} +\quad \underbrace{f\sharp}_{\text{major seventh}} \right\}\\ D^\triangle &= \left\{ \underbrace{d, f\sharp, a}_{D \text{ major triad}} +\quad \underbrace{c\sharp}_{\text{major seventh}} \right\}\\ B\flat^\triangle &= \left\{ \underbrace{b\flat, d, f}_{B\flat \text{ major triad}} +\quad \underbrace{a}_{\text{major seventh}} \right\}\\ \end{aligned}

The same principle applies to the other seventh chords. A m7\minor7-chord is made up out of a minor triad and a minor seventh.

Gm7={g,b,dundefinedG minor triad+fundefinedminor seventh}Dm7={d,f,aundefinedD minor triad+cundefinedminor seventh}Bm7={b,d,fundefinedB minor triad+aundefinedminor seventh}\begin{aligned} G\minor7 &= \left\{ \underbrace{g, b\flat, d}_{G \text{ minor triad}} +\quad \underbrace{f}_{\text{minor seventh}}\right\}\\ D\minor7 &= \left\{ \underbrace{d, f, a}_{D \text{ minor triad}} +\quad \underbrace{c}_{\text{minor seventh}}\right\}\\ B\flat\minor7 &= \left\{ \underbrace{b\flat, d\flat, f}_{B\flat\text{ minor triad}} +\quad \underbrace{a\flat}_{\text{minor seventh}}\right\} \end{aligned}

Here are some examples of 77-chords, known as dominant chords for reasons that will become clear in the next post about chord progressions.

G7={g,b,dundefinedG minor triad+fundefinedminor seventh}D7={d,f,aundefinedD minor triad+cundefinedminor seventh}B7={b,d,fundefinedB minor triad+aundefinedminor seventh}\begin{aligned} G7 &= \left\{ \underbrace{g, b, d}_{G \text{ minor triad}} +\quad \underbrace{f}_{\text{minor seventh}}\right\}\\ D7 &= \left\{ \underbrace{d, f\sharp, a}_{D \text{ minor triad}} +\quad \underbrace{c}_{\text{minor seventh}}\right\}\\ B\flat7 &= \left\{ \underbrace{b\flat, d, f}_{B\flat\text{ minor triad}} +\quad \underbrace{a\flat}_{\text{minor seventh}}\right\} \end{aligned}

You should be able to assemble the other seventh chords yourself, based on the information in this table:

NameNotation exampleBase triad typeSeventh type
Major seventhCC^\triangleMajorMajor
DominantC7C7MajorMinor
Minor seventhCm7C\minor7MinorMinor
Minor majorCmC_\minor^\triangleMinorMajor
DiminishedCoC^oDiminishedDiminished (enharmonically equivalent to M6M6)
Half-diminishedCøC\text{\o}DiminishedMinor

And this decision tree may help you structure the various types of seventh chords into categories in your mind. Don't worry if it the information does not seem very actionable right now, the next part about chord progressions will help a lot with that.

m3
b5
bb7
m7
P5
M7
m7
M3
M7
m7
7
Start
Minor, half-diminished or diminished
Half-diminished or diminished
o7, diminished
ø, half-diminished
m7 or minor major
Minor major
Minor 7
Major
Δ