Seventh chords are essential components of expanding your harmonic repertoire on the piano, helping shape its mood and texture across almost every genre of music.
To identify a seventh chord, draw its root on a staff and add notes in groups of third, fifth and seventh intervals above it to form a triad that indicates its quality.
Major Seventh
The major seventh chord is one of the most frequently occurring seventh chords in music. This four note chord combines major thirds on top of its root note to form what’s known as an extended seventh interval above it; hence its name “major seventh.”
These chords are inherently dissonant and must be resolved, usually via a falling fifth root motion, to produce sonority whose fifth is one step below seventh in pitch.
The major seventh chord is an integral component of functional harmony and can often be found in classical music, as well as being featured prominently across other popular genres such as pop and jazz music.
Minor Seventh
Minor seventh chords take a triad and add another note one fifth above its root, creating a dissonant interval and giving the chord an entirely unique sound and texture. You’ll often hear these chords in jazz, R & B or other popular music genres.
To play a minor seventh chord, draw the root of a triad on the staff before drawing an extra-long snowperson representing notes a third, fifth and seventh above it (imagine stacking these scale degrees like thirds). Add any accidentals from your key signature as necessary before considering what qualities should define this chord.
Just like triads, seventh chord qualities correspond directly with scale degrees; therefore they remain the same across keys, making memorizing chords much simpler for newcomers. This makes learning chords much simpler for beginners!
Dominant Seventh
Pop music styles like rock, blues and country often use dominant seventh chords to add tension through their flat 7th interval and create an emotional climax in songs. These tension-inducing chords add tension with their flat seventh interval that creates tension for dramatic effect in songs.
These chords consist of a major triad with an added minor seventh above its root note, similar to V triads but without an added V element. Similar to their V counterparts, these chords resolve back into a tonic chord for resolution.
The upper structure of a chord may change depending on which mode you’re playing in, so improvisers and comping instruments should strive to find out together what sounds best at any given time. Beginners may benefit from sticking to basic shapes of these chords until you become more comfortable using them; later you may wish to experiment with more advanced options.
Half-Diminished Seventh
As with triad chords, seventh chords can also be classified according to their interval qualities; however, unlike their triad counterparts which can also be identified according to inversion characteristics, seventh chords don’t always follow this rule.
Example: A dominant seventh chord with a diminished seventh cannot be inverted as its third has already been reduced an octave; however, a minor seventh diminished seventh can be reversed since both its second and fourth tones have also been decreased by an octave.
As with major seventh chords with major sixths, a major seventh chord with major sixth can also be inverted by raising both its fifth and root notes by an octave; for this reason seventh chords may also be inverted by taking its initial note and moving it up an octave toward its conclusion.
Tertian Seventh
These chords have an engaging sound, often seen in jazz music. To ensure maximum effectiveness for you and your musical style, use these chords sparingly and only after testing them out first.
Simple major or minor triads with an added seventh interval give chords more of a chromatic sound than their diatonic counterparts, which can help create melodies with multiple tones.
Some books refer to them as tertian chords when their triad type is unspecified and their seventh interval can either be major or minor; this approach is also sometimes applied to non-tertian seventh chords like major sixth (see Figure 18-9 for an example) which require special care when voice leading in order to prevent dissonances from developing.