Western music (European music) is also called "triadic music" because the harmonic structure is based on chords, usually three-note chords. Three-note chords (the root, third and fifth of any key) are called triads. Add a minor third and you have a 7th chord. There are also 9th, 11th and 13th chords, particularly in jazz, but when we study music theory we start with triads and seventh chords.
Three note chords (triads) can have two inversions; four note chords (seventh chords) can have three inversions:
• If the the root of the chord is in the bass, you have a root position chord.
• If the third is the lowest note, you have a first inversion.
• If the fifth is in the bass, you have a second intersion.
• If the seventh is in the base, you have a third inversion.
Example (C Major - I chord):
• Root Position, C in the bass - from the bottom up: C, E, G (E & G may be switched, as long as the lowest note is C). Written: I
• First Inversion, the third of the chord, E, is in the bass - from the bottom up: E, G, C (G & C may be switched, as long as the lowest note is E). Written: I6
• Second Inversion, the fifth of the chord, G, is in the bass - from the bottom up: G, C, E (C & E may be switched, as long as the lowest note is G). Written: I
The following represents the Root Position and First and Second Inversions of the I chord in C Major. These are labeled as: I, I6, and I .
Example (C Major - V7 or "dominant seventh" chord):
• Root Position, G in the bass - from the bottom up: G, B, D, F (B, D & F may be switched, as long as the lowest note is G). Written: V7
• First Inversion, the third of the chord, B, is in the bass - from the bottom up: B, D, F, G (G, D & F may be switched, as long as the lowest note is B). [Note that the major second, F-G, written on either site of the note stem, is characteristic of the dominant seventh chord in its inversions.] Written: V
• Second Inversion, the fifth of the chord, D, is in the bass - from the bottom up: D, F, G, B (F, G & B may be switched, as long as the lowest note is D). Written: V
• Third Inversion, the seventh of the chord, F, is in the bass - from the bottom up: F, G, B, D (G, B & D may be switched, as long as the lowest note is F). Written: V
|