Watch the Diatonic online guitar lesson by Joe Dalton from Fretboard Epiphanies

Diatonic- consisting of half steps and whole steps. The notes of a major scale without any other notes. There are two phrases to describe the use of the word “diatonic” as it pertains to our studies. The chords that result from any major scale are:

Major
Minor
Minor
Major
Major
Minor

Diminished

The first triad (3 note chord) uses the 1st, 3rd, and fifth notes of the scale. This chord is major. The second triad uses the 2nd, 4th, and 6th notes of the scale. This chord is minor. A major triad has two steps between the first two notes and a step and a half between the next two notes. A minor triad has a step and a half between the first two notes and two steps between the next two notes.

The 1st note is known as the root of the triad. Every triad has a root third and fifth. If the triad is built on the 2nd, 3rd, 4th etc. scale degree, we still refer to the first note as the root. Another way to look at the construction of chords is by intervals.

An Interval is the distance between the notes. Always count the note you are starting with. The distance between A and C is a third.

A major third is 2 steps.
A minor third is 1½ steps.
A major triad is a major 3rd with a minor 3rd on top.
A minor triad is a minor 3rd with a major 3rd on top.
A diminished triad is a minor 3rd with a minor 3rd on top.

This makes the length of the triad shorter (only 3 steps), hence the name diminished. (made smaller) The remaining triad does not occur in a major scale. The augmented triad is a major 3rd with a major 3rd on top. So this triad is longer. Augmented - made bigger.