What is Harmonizing a Scale?
Harmonizing a scale means building a chord on each scale degree using only the notes belonging to that scale. By taking a note (the **Root**), skipping the next scale note, taking the next one (the **Third**), skipping the next, and taking the next (the **Fifth**), we stack thirds to build a three-note chord called a **Triad**. Stacking one more third (the **Seventh**) creates a **7th Chord**.
This interactive tool shows you exactly which chords belong to which keys, maps them visually on a note wheel, a piano, and a guitar fretboard, and lets you play them to hear their character.
Harmonized Degrees
Understanding Modal Chords in Folk Music
What is a "Mode"?
A mode is a permutation of the major scale. If you play the notes of the **C Major scale** starting on **C**, you are in the **Ionian mode (Major)**. But if you play the exact same notes (no sharps, no flats) starting on **D**, you are playing in **D Dorian**. Because the home note (tonic) has shifted to D, the intervals change, creating a minor, mysterious sound.
Irish Traditional Modes
Traditional Irish tunes are modal. You will frequently encounter:
- Major (Ionian): Happy, bright. e.g. Cooley's Reel (G major).
- Mixolydian: Major-like, but with a flattened 7th (b7) giving a bluesy or bagpipe-like feel. e.g. The Morrison's Jig (E Mixolydian).
- Dorian: Minor-like, but with a raised 6th note, creating a haunting, driving sound. e.g. Drowsy Maggie (E Dorian).
- Aeolian (Natural Minor): Sad, dark, and soft. e.g. The Star of Munster (A Aeolian).
Modal Chord Functions
Accompanists (guitar/bouzouki players) use modes to find chord substitutions. For example, in **D Dorian** (which uses the notes of C Major), the major IV chord is **G Major**, and the flattened 7th chord is **C Major**. Accompanying a Dorian tune using standard minor scale chords (like A minor or G minor) would clash, because the raised 6th note of Dorian dictates a G Major chord!