Notes of a chord

What it's for

To know which notes to play for a chord, handy on piano, guitar or for theory. It recognizes major, minor, sevenths, sus, dim, aug and more.

How to write the chord

Use international notation: C, D, E, F, G, A, B. Examples: «C» (C major), «Am» (A minor), «G7», «Dmaj7», «Fsus4».

How a chord is built

Almost every chord is built by stacking thirds, that is by skipping every other note of the scale. From a C you take the E and then the G, and out comes a C major. If the middle note drops by a semitone, it becomes C minor: that single semitone is the difference between cheerful and wistful, and it is why the same song changes character when one finger moves.

Adding a fourth note gives the sevenths, which introduce tension and ask to resolve: the dominant seventh (G7) pulls towards C the way a question pulls an answer, and it is the cadence that closes millions of songs. Ninths, elevenths and thirteenths keep stacking thirds and are the typical colour of jazz and bossa nova.

The names that confuse

C7 and Cmaj7 are not the same thing and the difference is large: the first has a minor seventh and is a tension to resolve, the second a major seventh and is a relaxed, almost suspended chord. Writing one for the other changes the colour of a whole piece.

Cm7 is different again: it is the minor chord with a minor seventh, the typical timbre of soul and funk progressions. And sus chords are neither major nor minor, because the third, the very note that decides the character, is replaced: sus4 with the fourth, sus2 with the second. That is why a sus sounds undecided and asks to dissolve into the full chord.

Why the same note has two names

F sharp and G flat are the same key on the instrument, but in writing they are not interchangeable: inside a chord every note has a role, and its name says which. In a D major the third is called F sharp and not G flat, because it has to be a kind of F: written as a G, the chord would have two Gs and no F, and on paper it would no longer read.

On guitar or piano the distinction looks like pedantry; it becomes concrete as soon as you read a score, transpose a piece or write for other instruments. And it explains why some chords carry names that look absurd, like E sharp or C flat: they are not errors, they are the same note called by the name that context requires.

Inversions, and why two identical chords sound different

The notes of a chord can be played in any order, and the chord stays the same: C-E-G and E-G-C are both a C major. What changes is the lowest note, and that is heard: it is called an inversion, and it is written with a slash, like C/E, meaning «C major with E in the bass».

It serves something very practical: making the bass walk by steps instead of leaps. A sequence C, G/B, Am has a bass falling C-B-A, and the move sounds smooth where three root-position chords would sound stepped. It is one of the most used and least explained tricks in accompaniment.

Nearby tools

For guitar fingerings there is Guitar chords, to change key Transpose chords and to build a sequence Chord progressions. The theory behind it is in Musical scales, Musical intervals and Circle of fifths.