A seventh chord adds an entirely different dynamic to a triad, making them so iconic.
In chord-symbol notation, when the seventh note occurs in the lowest voice it is written with a slash before its name; for example: G7/F.
Adjusting the relationship between third and seventh can alter its quality; there are six different seventh chord qualities.
Major Seventh
The major seventh chord is an ideal choice for songwriters as it sounds pleasing while providing extra tension in a progression. While commonly employed in jazz and pop music, its use may not be seen as frequently in blues or other heavier genres.
An effective way to form a major seventh chord is to start with a major triad and add one note that is half step lower than its root note – for instance, to create C major seventh (CMaj7) chord, begin by starting with notes of C major triad before adding B as needed.
Seventh chords can usually be resolved using falling-fifth and rising-fourth root motion, like triads. Chords built on sol and fa consist of a minor triad with a major seventh note while those built on me, re and ti are either semi-diminished (consisting of diminished triad with reduced seventh) or fully diminished (containing diminished triad with an augmented seventh). The major seventh chord is one of the most frequently-used seventh chords found within music today – as such it’s also one of its most versatile members!
Minor Seventh
Minor seventh chords add a note an octave higher to an existing triad, creating a warm sounding chord found often in romantic songs.
Major sevenths can be constructed in any scale degree and provide richer textures than their triad counterparts by including dissonance. Like major sevenths, major sevenths also contain both a fifth and root note.
To play a minor seventh chord, draw its root note on the staff and add any accidentals from its key signature above it. Next, draw an extra-long snowperson representing notes third, fifth and seventh above its root note. Identify these chords on the staff before playing them!
Dominant Seventh
The dominant seventh is one of the most ubiquitous of tertian seventh chords, appearing frequently across musical genres and styles. You might hear Elvis singing about its presence in “Heartbreak Hotel.” Its combination of A7, B7 and E7 gives this chord its signature swagger and may cause you to shake your hips slightly in response.
To create a dominant seventh chord, begin at its root and draw an extra-long snowperson with all notes stacked together for representation of your triad – don’t forget any accidentals from your key signature as necessary!
Notably, the 5th of the dominant seventh may be altered – often written enharmonically on lead sheets as +9 or -9 for convenience – unlike all interval qualities must agree in their major thirds – meaning its root, 3rd and 7th should all remain the same – this relationship is known as voice leading.
Half-Diminished Seventh
As we’ve seen, adding a seventh interval changes the chord’s quality significantly; these differences can further be described by its type of triad and seventh buildup.
An example of a minor seventh chord construction could involve stacking two thirds up from the root and then evaluating their interval relationships to each note that makes up that chord’s quality.
Half-diminished seventh chords follow this same approach. To construct one from any triad, simply add a diminished seventh on top and you have yourself a half-diminished seventh chord!
For inverting a 7th chord, take the note G from its chord that needs inverting and move it up an octave until it ends up at the end of it – this can be shown using figured bass notation as 6/4/2.