The Anatomy of a Chord

Introduction: Acoustic Architecture

Up to this point we've looked at music horizontally, measuring the distance from one note to the next. But music rarely exists as a single line. When we stack notes and sound them together, we create harmony.

Just as a building relies on load-bearing columns, harmony relies on stacking specific intervals. The most fundamental structure in tonal music is the triad: a three-note chord built from stacked thirds.

Click any example to hear it: each chord is played broken, then together.

Building the Triad

A triad starts from a root, the note that names the chord. Stack a third on top of it to get the third, and another third on top of that to get the fifth (a fifth above the root).

The GBDFACE chain from Chapter 1 does this instantly: every triad is three neighbors in the chain. Root G gives G–B–D; root A gives A–C–E; root F gives F–A–C. On the staff, a root-position triad is always three notes on three consecutive lines, or three consecutive spaces, like a snowman.

Spell the letters first, then add accidentals. F♯ minor is spelled F♯–A–C♯: the letters F–A–C come from the chain, and only then do we adjust the accidentals to get the right quality.

The Four Triad Qualities

The chain of letters gives you the notes; the exact size of each third gives the triad its quality:

A quick check for major and minor triads: if the fifth is perfect, look at the bottom third. A major third on the bottom means a major triad; a minor third means minor.

Seventh Chords

Stack one more third on top of a triad, and you get a seventh chord: root, third, fifth, and seventh. The seventh adds a layer of dissonance that pushes the music forward. Five qualities of seventh chord are common in tonal music, named by their triad plus the quality of the seventh:

The dominant seventh is by far the most important. It contains a tritone between its third and seventh, which gives it an overwhelming pull toward resolution (Chapter 6).

Inversions

A chord with its root in the lowest voice is in root position. Put another chord member in the bass and the chord is inverted. The upper notes can be in any order; only the bass note decides the inversion.

• First inversion: the third is in the bass.
• Second inversion: the fifth is in the bass. This position is unstable, because of the fourth above the bass (Chapter 4), and has its own rules (the Six-Four Chords chapter).
• Third inversion (seventh chords only): the seventh is in the bass.

To identify an inverted chord, rearrange its notes into a stack of thirds. The bottom of that stack is the root.

Figured Bass

In the Baroque era, keyboard players read a single bass line with numbers under it: a shorthand for which intervals to build above the bass. We still use this figured bass today to name inversions. The numbers are intervals above the bass note (not the root), and we usually abbreviate them:

One way to remember the seventh-chord figures: they count down. 7, 6/5, 4/3, 4/2.

Lead-Sheet Symbols

Jazz and pop musicians name chords with lead-sheet symbols instead: the root's letter plus a quality suffix (see the tables above). An inversion is shown as a slash chord, with the bass note after the slash: C/E is a C major triad with E in the bass, the same thing a classical musician would figure as a 6.

Both systems describe the same notes. Figured bass and Roman numerals (Chapter 6) show a chord's function in a key; lead-sheet symbols show its name and are independent of key. You'll use both.

Try It: Chord Builder

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