Every Dominant Chord in Jazz, Explained

V7/IV resolves to the subdominant (fourth degree) with fundamental as the first note of the scale (D7 in C major). Unlike the first degree diatonic chord which must be on a strong beat, V7/IV must be placed on a weak beat. The difference from the diatonic IV chord (Fmaj7) is the third: minor in diatonic, major in V7/IV. V7/V resolves to the dominant (fifth degree) with fundamental as the second note of the scale (E7 in C major). The difference from the diatonic ii chord (Dm7) is the third: minor in diatonic, major in V7/V. V7/V creates a situation of two consecutive dominants (V7/V resolving to V7, which then resolves to I). Both chords are widely used in popular music.

In a major key, there are seven diatonic chords identified by Roman numerals: I (one) is major, II (two) is minor, III (three) is minor, IV (four) is major, V (five) is major, VI (six) is minor, and VII (seven) is diminished. These are also called Nashville numbered chords. The pattern is consistent across all major keys.

The dominant tonic (V7) is a powerful tool for harmonizing melodies, as demonstrated by alternating between tonic and dominant chords throughout a scale (such as C major), which creates a coherent harmonic progression that can be applied both diatonically and chromatically.

This section explains how to analyze chord progressions using Roman numerals, a universal system for describing harmonic relationships. In any major key, seven diatonic chords exist: I, IV, V are major; ii, iii, vi are minor; vii° is diminished. For example, in C major: C (I), F (IV), G (V) are major; Dm (ii), Em (iii), Am (vi) are minor; Bdim (vii°) is diminished. This system allows musicians to describe progressions like 'I-VI-IV-V' universally across all keys. The video demonstrates this with Tom Petty's 'Learning to Fly,' showing how F-C-Am-G progression translates to IV-I-vi-V in C major. Understanding this framework enables meaningful musical discussions and deeper appreciation of song structures.

In jazz piano, chord extensions (9th, 11th, 13th) are notes added above the 7th of a chord, built by stacking thirds from the root (1-3-5-7-9-11-13), and are always derived from the major scale of the chord's root; chord tones (root, 3rd, 5th, 7th) define the chord's quality, while extensions add harmonic color, and altered extensions (b9, #9, #11, b13) are created by sharpening or flattening the natural extensions, with these four alterations commonly found over dominant 7th chords.

Musical intervals (second through octave) form chord foundations. Extensions (ninth, eleventh, thirteenth) occur when notes double an octave higher. The seventh acts as a bridge to extensions and must always be present. Only the ninth can be both flattened and sharpened. The eleventh can only be sharpened (no flat eleventh exists). The thirteenth can only be flattened (no sharp thirteenth exists). Extensions are named by distance from root: ninth = second, eleventh = fourth, thirteenth = sixth. Understanding these principles enables effective chord construction.

Western music theory uses a seven-note scale structure (major and minor scales), which explains why interval numbering stops at seven. In a major scale, scale degrees correspond to: 2nd = Major Second, 3rd = Major Third, 4th = Perfect Fourth, 5th = Perfect Fifth, 6th = Major Sixth, 7th = Major Seventh. In a minor scale, 3rd becomes Minor Third, 6th becomes Minor Sixth, and 7th becomes Minor Seventh. Extended chord tones (9ths, 11ths, 13ths) are not new intervals but the same pitches as smaller intervals an octave higher, since the 8th note equals the octave (same as the root). This creates the equivalences: 9th = 2nd, 11th = 4th, 13th = 6th.

Chord extensions (9ths, 11ths, 13ths) are built by continuing to ascend the scale from a basic triad (root, third, fifth), with the 9th being the same note as the 2nd, the 11th being the same as the 4th, and the 13th being the same as the 6th; the essential notes that define any chord are the root, third, and seventh, while extensions add color and tension, with sharp 11ths commonly used in major 7th chords to avoid clashing with the third, and dominant chords allowing for more varied alterations like flat 9ths and flat 13ths.

To alter chord extensions, use sharps (#) to raise a note by a half step and flats (b) to lower a note by a half step. For example, C7 with a flat 9 means you take the standard C7 chord (1, 3, 5, 7) and replace the 9th (D) with D flat. Similarly, C11 with a flat 9 means you take the standard C11 chord (1, 3, 5, 7, 9, 11) and lower the 9th to D flat.

The major scale has modes that create distinct tonalities. Lydian (fourth mode) is like major but with a raised fourth degree, creating a bright, transcendental sound. Mixolydian (fifth mode) is like major but with a lowered seventh degree, creating a slightly darker, more laidback sound. These modes demonstrate how changing single scale degrees transforms the emotional character of music while maintaining the same root note.

The Mixolydian mode is the fifth mode of the major scale. It is similar to the major scale but with a lowered seventh degree, which serves as its character note. This lowered seventh degree pacifies the leading tone effect, making the scale feel more laid-back and less directional. Mixolydian is surprisingly common in rock music, often functioning as the 'rock version' of the major scale. Examples include 'Clocks' by Coldplay and 'Bittersweet Symphony' by The Verve.

Mixolydian is a mode of the major scale with a flat seventh (A flat) and major third (D), creating a dominant, bluesy quality. The notes used throughout the song (A flat, B flat, C, D, E flat, F, G) form the E flat major scale. By moving the bass note while keeping the same note bank, musicians can create different chords and modes without changing the actual notes. This demonstrates how a single parent scale can serve as the foundation for multiple harmonic possibilities.

Mixolydian mode is created by taking a major scale and flattening the seventh note, creating a bluesy edge while maintaining the major third. This works better for chord changes because the flat seven creates tension that pulls your ear to the next chord. To find which major scale corresponds to a Mixolydian mode, ask what note is the fifth of your chord: G Mixolydian uses C major scale (G is fifth of C), C Mixolydian uses F major scale (C is fifth of F), and D Mixolydian uses G major scale (D is fifth of G). Your fingers already know the major scale positions, so the challenge is understanding the theory rather than the fingerings.

The Mixolydian scale is the fifth mode of the major scale and is used on the dominant chord (the five chord), which creates dissonance and resolves to the tonic (one chord). In 'The Man Who Sold the World,' the bassline uses B Mixolydian (the five chord) which takes us back to E major (the one chord). B Mixolydian consists of B (root), C# (major 2), D# (major 3), E (perfect 4), F# (perfect 5), G# (major 6), and A (minor 7). The E major scale consists of E (root), F# (major 2), G# (major 3), A (perfect 4), B (perfect 5), C# (major 6), and D# (major 7). This demonstrates how Mixolydian and major scales work together in music, with the Mixolydian scale on the dominant chord resolving to the major scale on the tonic chord.