Lesson 45 of 72 · I, IV, V and the dominant seventh
The key of C major uses seven notes: C D E F G A B, all the white keys. Build a chord on each one, always using every other white key: you get the seven chords of the key.
They’re numbered with Roman numerals, based on their root: I on C, II on D, III on E… Major chords are written in capitals (I, IV, V), minor chords in lowercase (ii, iii, vi).
The seven chords of C major
Why this way: Why numbers instead of names? Because they tell you the chord’s role in the key: I – IV – V is the same progression in every key. Nashville studio musicians even write their chord charts with nothing but numbers: that way, a song can be transposed in the blink of an eye.
The chords of C major, called by their Roman numerals. Every octave and every order of notes is accepted.
The I chord is the tonic: home, rest. The V chord is the dominant, and the IV chord is the subdominant.
Add a fourth note to G major, another 3rd higher: G – B – D – F. That’s the dominant seventh chord, written G7 (“G seven”). The F creates a tension that wants to resolve: B goes up to C, F goes down to E… and you land back on the C chord.
G7 in the right hand: fingers 1-2-3-5.
Did you know?: The 7 in G7 comes from counting notes up from G: G, A, B, C, D, E, F. F is the 7th above G.
C, F, G7, C: your right hand keeps the same shape, and adds the pinky on F for G7 (1-2-3-5).
As many chords as you can in 60 seconds! Major, minor and G7, any octave, any order of notes.
Tonic, subdominant, dominant, tonic: listen to the tension of G7 resolve to C. The most famous cadence in music: two half notes per chord, in the right hand. The computer plays the bass.