How Chords Are Built: Harmony From the Major Scale

Every chord you play on guitar has a direct relationship to a scale. When you strum a C major chord, you are playing three notes from the C major scale simultaneously. The chord is not separate from the scale. It is extracted from it.

This connection is why understanding scales makes learning chords easier. Once you see chords as scale notes played together, the fretboard becomes a unified system rather than disconnected shapes and patterns.

In Level 2, you learned that each scale degree has a specific sound and function. Chords inherit these functions. A chord built on the 5th degree carries the dominant tension of that degree. A chord built on the 1st degree carries the stability of the tonic.

The most basic chord is a triad, made of three notes. To build a triad, you take a scale degree as your root, skip one note, take the next (the 3rd), skip another, and take the next (the 5th).

This "skip one, take one" pattern is called stacking in thirds. Each note is a third interval above the previous one.

This 1-3-5 formula works from any scale degree. The root gives the chord its name. The 3rd determines if it sounds major or minor. The 5th provides stability and fullness.

The interval from the root to the 3rd determines the chord quality. A major third (4 semitones) creates a major chord. A minor third (3 semitones) creates a minor chord.

Notice that both triads span 7 semitones from root to 5th. The difference is where the 3rd falls within that span. This single note, one semitone higher or lower, transforms the entire emotional character of the chord.

On guitar, this means shifting one finger by one fret changes a major chord to minor. The shapes are almost identical because the underlying structure is almost identical.

The 1-3-5 combination is not arbitrary. These degrees represent the most consonant intervals in music.

• The root (1) establishes the tonal center
• The 5th creates the most stable interval (perfect 5th)
• The 3rd adds color while maintaining consonance

Together, these three notes create a sound that is harmonically complete but simple enough to blend with other musical elements. This is why triads are the foundation of Western harmony.

The remaining scale degrees (2, 4, 6, 7) can be added to triads to create richer chords. The 7th is most common and will be covered later in this level. But even the most complex jazz chord contains a triad at its core.

Every chord shape you know contains the root, 3rd, and 5th arranged across the strings. When you play a C major open chord, you are playing:

The chord shape is just an efficient way to play the same three notes in multiple octaves. Different voicings and inversions rearrange these notes, but the core remains 1-3-5.

When you visualize a scale position on the fretboard, the chord tones are embedded within it. The root, 3rd, and 5th of the scale are also the root, 3rd, and 5th of the I chord. Seeing these connections lets you switch between melodic (scale) and harmonic (chord) thinking instantly.

An arpeggio is simply a chord played one note at a time. When you understand how chords are built, you understand arpeggios automatically.

Playing a C major arpeggio means playing C, E, and G in sequence rather than simultaneously. The notes are identical to the chord. Only the rhythm changes.

This connection is why Level 4 will focus on arpeggios. Once you see chord tones across the fretboard, you can outline any chord melodically. This is the foundation of chord-tone soloing.