How Chords Are Built | Chordier lessons

A chord name is a compressed formula. Once you know the formula, you can decode any chord - not just the ones you've memorized. That's the difference between recognizing shapes and actually understanding the instrument.

The Major Triad: 1-3-5

Every chord starts with a triad: three notes built by stacking thirds above a root. The major triad uses the 1st, 3rd, and 5th degrees of the major scale.

In C major: C (1), E (3), G (5). That's C major.

Root to 3rd: a major 3rd (4 half steps). 3rd to 5th: a minor 3rd (3 half steps). The bright, stable sound of any major chord comes from that specific stack of intervals.

The Minor Triad: 1-b3-5

Flatten the 3rd by one half step. That's the only change between major and minor.

In A minor: A (1), C (b3), E (5).

Root to b3: minor 3rd (3 half steps). b3 to 5th: major 3rd (4 half steps). The order inverts - minor 3rd first, then major - and the sound shifts darker. One note. One half step. That's all that separates major from minor.

7th Chords

Add another third above the 5th and you get a 7th chord:

Major 7th (maj7): 1-3-5-7. Cmaj7 adds B to the C chord. Smooth and slightly jazzy.
Dominant 7th (7): 1-3-5-b7. G7 has an F instead of F#. Creates strong pull toward the tonic.
Minor 7th (m7): 1-b3-5-b7. Am7 is Am with an added G. Warmer and more complex than plain Am.

The dominant 7th (G7 resolving to C, or D7 resolving to G) is the strongest resolution movement in Western harmony. If a chord symbol shows "7" without "maj", that tension is intentional.

Reading Chord Symbols

The system is consistent:

G = 1-3-5 (major triad)
Gm = 1-b3-5 (minor triad)
G7 = 1-3-5-b7 (dominant 7th)
Gmaj7 = 1-3-5-7 (major 7th)
Gm7 = 1-b3-5-b7 (minor 7th)
Gdim = 1-b3-b5 (two minor 3rds stacked)
Gaug = 1-3-#5 (two major 3rds stacked)

Practice Exercise

Take the G major scale: G A B C D E F#. Build triads on each degree by taking every other note. Start on G: G B D (G major). Move to A: A C E (A minor). To B: B D F# (B minor). To C: C E G (C major). Continue through the scale. These are the seven diatonic chords of G major - all chords that naturally belong in the key. The pattern: major-minor-minor-major-major-minor-diminished. Recognize it. You'll see it everywhere.

Questions and Answers

What makes a chord major or minor?: The difference between a major and minor chord is the 3rd. In a major chord, the interval from root to 3rd is a major 3rd (4 half steps). In a minor chord, the 3rd is flattened by one half step (minor 3rd, 3 half steps). This single note change produces the characteristic bright vs. dark quality difference.
What is a dominant 7th chord and why does it resolve?: A dominant 7th chord (such as G7) uses the formula 1-3-5-b7. The b7 creates a tritone interval with the 3rd that produces harmonic tension. This tension resolves naturally when the chord moves to the tonic: G7 resolves to C, D7 resolves to G. This resolution is the most fundamental motion in Western harmony.

Next up: Chord Inversions: Bass Notes and Voice Leading - developing the ability to identify these intervals and chord qualities by sound.