So far, most chords in the lessons belong to the key you're in - diatonic chords. But some of the most beautiful and surprising moments in music come from using chords that don't belong to the key. These are chromatic chords - they use notes outside the scale to add colour, tension, and unexpected turns. Their effect depends on how the altered notes connect to the surrounding chords and melody.
half a beat or a beat - and connect two chords by supplying stepwise bass or inner-voice motion.Diatonic vs chromatic
Diatonic (in the key)
Expected. Safe. Consonant.
Chromatic (outside the key)
Unexpected. Colourful. Surprising.
Secondary dominants
A secondary dominant is when you treat any chord in the key as a temporary tonic and play its V7 chord before it. This creates a miniature V-to-I resolution within the key. Written as "V/x" (five-of-x).
Secondary dominants in C major
D7 before G (V/V) is a familiar secondary dominant because it tonicises the dominant of C. The F-sharp in D7 points toward G; whether the colour reads as blues, gospel, pop, or something else depends on the voicing, rhythm, and surrounding arrangement.
Chromatic mediants
Chromatic mediants are major or minor chords whose roots are a third (3 or 4 semitones) away from the current chord, and which share at least one note. The shared tone can smooth the connection while the chromatic root movement creates contrast; the resulting colour depends on voicing and context.
Chromatic mediants from C major
Eb
3 semitones down
E
4 semitones up
Ab
4 semitones down
A
3 semitones down
C to Ab is the classic film score sound - epic and sweeping
Chromatic passing chords
Like passing tones in melody, chromatic passing chords fill gaps between diatonic chords by half step. They're brief - usually lasting half a beat or a beat - and connect two chords by supplying stepwise bass or inner-voice motion.
Chromatic passing chord between Dm and Em
D#dim slides between Dm and Em - smooth chromatic bass movement
Borrowed chords (modal interchange)
Borrowed chords come from the parallel key - the key with the same root but opposite quality. If you're in C major, you can borrow chords from C minor. These are technically chromatic because they use notes outside your key's scale.
Common borrowed chords in C major (from C minor)
iv (Fm)
Dramatic, melancholic
bVII (Bb)
Rock staple, rebellious
bVI (Ab)
Lowered 6th with a wider chromatic shift
bIII (Eb)
Warm, unexpected
Using it tastefully
Use a clear contrast
One well-placed chromatic chord can stand out when the surrounding harmony is diatonic. Its effect comes from the contrast between the altered notes and the current key.
Resolve back to the key
After a chromatic detour, return to a diatonic chord. The temporary departure makes coming home sound sweeter.
Use smooth voice leading
Chromatic chords work best when individual voices move by half step. This makes even exotic chords sound natural.
Try it
Tap to hear how a chromatic chord adds colour compared to a diatonic one:
The Db major does not belong to C major - that is what makes it surprising.
Two common chromatic chords in C major - borrowed from C minor
Key takeaway
Chromatic harmony uses chords from outside your key to alter the pitch content and harmonic direction. Secondary dominants create local resolutions, while chromatic mediants connect roots by a third with contrasting chord qualities. Passing chords connect diatonic chords by half step. Borrowed chords bring in chord qualities from the parallel key. Use each device where its voice-leading supports the surrounding progression.
Next: reharmonisation - keeping the same melody but changing the chords underneath.
Hear advanced harmony in action
Starts generates chord progressions using voice leading, tensions, and modulation.