Although all the triads in the scale are made up of thirds and pretty much look the same, the scale of chords generates several different types of triads:
Major, Minor, Diminished
The primary chords in every key are all major triads. They are always built above the first, fourth, and fifth note of the scale. We can always be sure in a major scale that these three chords are major. Therefore, the I, IV and V chords in any major key will always be major. The Roman Numerals for these chords are therefore written as capital letters. This may also explain why these three chords have become the primary chords--they are the only major triads in the scale.
There are also three minor triads (built on the second, third and sixth notes of the scale). See if you can hear the difference in their sound when compared to the primary chords. The Roman Numerals for these chords are most often written as lower case letters--ii, iii, vi.
The only diminished triad is the chord built on the seventh degree of the scale. It is one of the most unstable chords in the scale. See if you can hear how it would like to resolve to the tonic chord. The Roman Numeral for this chord is also a lower case letter--vii.
Play the examples several times to see if you can distinguish between the sound of the major and minor chords.
The major chords are usually considered "brighter" or "happier" sounding.
The minor chords are "darker" or "sadder" sounding. The triad built on the seventh degree of the scale is a diminished triad and is often associated with "suspense" or "scary" events. See if you can hear the subtle difference between the minor triads and the diminished triad.
Please continue with the next section of this lesson.
