Rounding up our current music theory section today we are going to look at those basic building blocks of almost all music; simple 3 note chords called Triads (nothing to do with Hong-Kong in this case).
A triad is constructed by taking any note (called the Root note) and adding two further notes above it. The first note added will be a third (counting the root note, so from A, for example, A, B, C – C is the third), above the root and is therefore called the third. If this note is a minor third (see here) from the root, the triad will be a minor chord. If it is a major third above the root, it will be a major chord (see exceptions below).
The second note to be added is a (usually) perfect fifth from the root.
Note. The third and fifth in a triad are the intervals from the root note of the triad (name note of the chord) and should not be confused with the third and fifth notes of the scale/key. The only place where these will be the same is in a triad on the key note of the scale e.g. a C Major chord in the key of C Major where C, E and G are the root 3rd and 5th of both the chord and the scale.
Staying in the key of C Major, if a triad on D is played, F and A are a third and a fifth from D. But D, F and A are the 2nd, 4th and the 6th notes in the key scale.
Major and minor triads are most common. Other triads can be constructed but these are less used. If a major third and an augmented fifth is used the triad is an augmented chord. If a minor third and a diminished fifth are used the chord is diminished.
Figure 1 shows the C Major scale. Each scale degree can be referred to by number as shown above.
Figure 2 shows Naturally Occurring thirds built on each scale degree. Use of the word naturally here refers to the fact that the notes all come from the scale they are built upon.
Figure 3 shows naturally occurring triads built on each scale degree by stacking a naturally occurring fifth on top of the root and the naturally occurring third (shown in Figure 2 ). Each triad can be referred to by a number (e.g. one chord, two chord, three chord, etc.), in this case roman numerals are commonly used. Capitals show a major chord, lower case shows minor. In the case of chord 7, this is actually a diminished chord in all major keys and is very rarely used.
When building triads on a major scale:
- I-chords are ALWAYS MAJOR
- ii-chords are ALWAYS MINOR
- iii-chords are ALWAYS MINOR
- IV-chords are ALWAYS MAJOR
- V-chords are ALWAYS MAJOR
- vi-chords are ALWAYS MINOR
- vii-chords are ALWAYS DIMINISHED
Many pop and rock songs actually adapt the scale so that chord 7 becomes a major chord on the flattened 7th of the scale, which technically means they are modal (we haven’t covered modes yet – they’ll be in our next theory session) rather than in a major key.