Approach chord

In music, an approach chord (also chromatic approach chord and dominant approach chord) is a chord one half-step higher or lower than the goal, especially in the context of turnarounds and cycle-of-fourths progressions, for example the two bar 50s progression:[3]

|G /  Em /   |Am /   D7 /   ||
I-vi-ii-V turnaround in G[1] Play .
I-vi-ii-V turnaround with approach chords in G Play .
I-vi-ii-V turnaround in F Play .
Approach chords in F Play .[2]

may be filled in with approach chords:

|G F9 Em Abm |Am D#7 D7 Gb7 ||

F9 being the half-step to Em, Am being the half-step to Am, D7 being the half-step to D7, and G7 being the half-step to G. G being I, Em being vi, Am being ii, and D7 being V7 (see ii-V-I turnaround and circle progression).

An approach chord may also be the chord immediately preceding the target chord such as the subdominant (FMaj7) preceding the tonic (CMaj7) creating a strong cadence through the contrast of no more than two common tones:[4] FACE – CEGB.

Approach chords may thus be a semitone or a fifth or fourth from their target.[5]

Approach chords create the harmonic space of the modes in jazz rather than secondary dominants.[6]