A 7th chord adds the 7th scale degree to a triad — major7 chords include the natural 7th, minor7 chords include the flattened 7th

A 7th chord is built from four notes: root, 3rd, 5th, and 7th. Whether the chord is major 7 or minor 7 depends on the scale: a major scale has a natural 7th (one semitone below the octave), a minor scale has a flattened 7th (two semitones below the octave). C major 7 = C, E, G, B; C minor 7 = C, Eb, G, Bb. The practical rule for conversion: to turn any major 7 chord into the minor 7 of the same root, lower both the 3rd and the 7th by one semitone. This is the foundational chord type of deep house, jazz-influenced soul, and many neo-soul genres, giving music a harmonically rich, ‘open’ quality compared to bare triads.

Examples

C major 7: C-E-G-B. C minor 7: C-Eb-G-Bb. F major 7: F-A-C-E. F minor 7: F-Ab-C-Eb. To convert any major7 chord to minor7 of the same root: lower the 3rd and 7th by one semitone each.

Assessment

Build a D major 7 chord from scratch (root, 3rd, 5th, 7th); then convert it to D minor 7 by applying the semitone rule; finally name the four notes in each chord.