The Major Scale, Modes & Triads

The 12 notes of western music

Western music uses 12 equally spaced pitches. Each step between adjacent notes is called a semitone (or half step), the smallest interval in western music. On a guitar, one semitone equals one fret.

The natural notes (A B C D E F G) are shown brighter. The sharps and flats sit between them. After the 12th note, the pattern repeats one octave higher with the same note names at a higher pitch.

The major scale: a specific pattern of 7 notes

A scale is a selection of notes from those 12, chosen using a specific interval pattern. The major scale picks 7 notes using this pattern of whole steps (W = 2 semitones) and half steps (H = 1 semitone):

Apply this pattern starting on C and you get C D E F G A B, which is the C major scale. The half steps fall between E and F, and between B and C. These happen to be the two places on the guitar where there is no fret between natural notes.

You can start this same pattern on any of the 12 notes and get a major scale in that key. Start on G and you get G A B C D E F#. Start on E and you get E F# G# A B C# D#. The pattern never changes, only the starting note does.

Modes: starting the same scale from a different note

Here is the key insight. The C major scale has 7 notes: C D E F G A B. If you play those same 7 notes but start from D instead of C, you get a completely different sound. Same notes, different starting point. That is a mode.

Each of the 7 notes in the major scale can be a starting point, giving you 7 modes. Each mode has a unique interval pattern, a unique character, and a unique triad built on its root.

Triads: the chords built from each mode

Every mode generates a triad by stacking every other note starting from its root: the root, the 3rd, and the 5th. Because each mode has a different interval pattern, the quality of the triad differs.

In C major, the 7 diatonic triads are:

The sequence of triad qualities is always the same in any major key: Major, Minor, Minor, Major, Major, Minor, Diminished. Change the key and the note names change, but that sequence never does.

This is why knowing the major scale unlocks everything. Once you know it, you know the 7 modes, the 7 diatonic triads, and the harmonic structure of every song written in a major key.

What this means on the guitar

Every time you play a chord progression in a major key, you are cycling through some of these 7 triads. A I IV V in G major is G, C, and D. A vi IV I V is Em, C, G, and D. These are the same 7 triads in different orders.

When you solo over those changes, you are not playing a different scale over each chord. You are playing the same major scale, but targeting the specific chord tones of whichever triad is playing at that moment. The scale gives you the notes. The modes tell you the character. The triads tell you where to land.