Seventh chords are created by adding a seventh interval above the root of a triad, similar to adding a sixth interval above it. Like triads, seventh chords can be stacked in close spacing without open gapping. Each note of a seventh chord has an interval name above it: such as C major seventh (I), F minor seventh (ii), or B half-diminished seventh (viio).
These four-note chords have more qualities than triads due to the way in which scale degrees can be altered, so we will discuss each type of quality type here.
Root
A seventh chord is a four-note chord composed of seven notes that adds the interval of a seventh note to the root triad chord. Seventh chords can create feelings of tension, power or even soulfulness depending on their dissonant qualities.
To identify a seventh chord, first locate its root. Sketch its shape onto a staff, adding notes for its triad and seventh above (imagine drawing an extended snowperson). Its quality will depend on what key signature its root holds.
Chords built on the first, third, and fifth scale degrees of a major scale are known as major chords; those composed on its second through sixth scale degrees are known as minor. A Bm7 chord contains a minor triad and seventh chord while G#ma7 contains major ones; when an seventh chord’s root contains accidentals it must also include these in its name (ie an F sharp is considered accidental in G#m7b5)
Third
Third of a Seventh Chord
To identify the quality of a seventh chord, draw its root on the staff before adding triads and sevenths above it to determine its quality. Notes of any seventh chord never fall more than an octave below their original positions – this holds true whether closed- or open-spacing sevenths contain doubled notes – making identification much simpler; yet practice with different sevenths in your key signature is essential in becoming familiar with all their variations.
Fifth
A seventh chord contains four notes and adds the fifth interval above a triad. As with triads, these chords can be stacked into various inversions; changing where the fifth sits affects its quality.
There are five distinct seventh chord qualities depending on where their fifth is positioned: major seventh (M7: major triad with major seventh above root), minor seventh (m7) and major-minor seventh (Mm7: major triad with an added minor seventh often known as dominant seventh) are all examples.
Diminished seventh chords are constructed using diminished triads with the addition of a diminished seventh. As their name implies, these chords do not include perfect fifths between root and sixth which gives rise to two tendency tones on either end resulting in more dissonant tones than major seventh chords; because of this feature, diminished sevenths are commonly used as transition chords towards major seventh chords one fifth lower down on their scale.
Seventh
The seventh chord is inherently dissonant and commonly used to add tension in music, yet over time and as audiences grow accustomed to its dissonance it has become part of many styles of music and have even become integral components themselves.
The dominant seventh chord consists of three intervals above its root note – a major third interval, perfect fifth interval and minor seventh interval – creating one of the most well-known types of seventh chords, and it can often be heard in blues and jazz music.
A half-diminished seventh chord consists of a diminished triad on its lowest note and a diminished 7th on top (commonly written as “dim 7 flat 5”). This chord is less dissonant than full diminished seventh chords since only its fifth note has been reduced by half step; making it closer to minor seventh chords than ever.