Building chords by steps

A step is a semitone: the distance between two adjacent keys, counting white and black alike. From C to C♯ is one step; from C to E is four.

That single measure describes any chord. C major is “four steps, three steps” from the root, and the formula holds from any other note: G major is four and three as well.

Triads are three-note chords and the starting point for everything else. Changing a single step turns a major into a minor, or a minor into a diminished.

Suspended chords replace the third — the note that decides whether a chord is major or minor — with the second or the fourth. The result is neither happy nor sad: it hangs, waiting to resolve.

Sixth chords add one more note without reaching the seventh, and the bare fifth (C5) keeps only the essentials.

The seventh adds a fourth note above the triad and is the threshold of modern harmony. The major seventh (Cmaj7) sounds wide and calm; the dominant seventh (C7) sounds unstable and pushes toward the next chord.

That tension is why G7 asks to resolve to C: it is the engine of the V–I progression.

Look at Cdim7: three steps, three steps, three steps. It is perfectly symmetrical, which is why its inversions all sound alike — a property that makes it very useful for modulating to distant keys.

Extended chords keep stacking thirds above the seventh. The large steps in these lists are not a mistake: they are the real jump to a note above the octave. C9 includes a D, C11 an F and C13 an A.

Past five notes, one hand’s five fingers run out. That is when you split the chord between both hands or drop notes — covered in two-hand chords and voicings.