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Chords are made up of linked intervals. The simplest type of chord is a triad, which is a three-note chord made up of two intervals. A chord is identified and labeled according to its root and its quality.
To determine the root of a triad, you first have to imagine that all of the notes in the chord have moved into the closest position on the staff—on three consecutive lines, or on three consecutive spaces. In this configuration, the bottom note is the root of the chord.
The rest of the notes in the chord are identified by their interval relationship to the root. For example, in a root-position triad, the note in the middle is called the "third" because it is a third above the root. The top note of the triad, then, is called a "fifth" because it is a fifth above the root.
The root of the chord is also the name of the chord. If the illustration above, for instance, were in treble clef, the root is C, so we'd say that this chord is a C chord. But is this C chord major, minor, augmented, dimished?
Quality
How can we tell whether it is major, minor, augmented, dimished?—in other words, how can we determine the chord's quality? Here are a few formulas to identify chord quality:
Major chord = root + a major third up from the root + a perfect fifth up from the root. Example: C (root) + E (third) + G (fifth).
Minor chord = root + minor third up from the root + perfect fifth up from the root. Example: C (root) + Eb (third) + G (fifth).
Diminished chord = root + minor third up from the root + diminished fifth (tritone) up from the root. Example: C (root) + Eb (third) + Gb (fifth). Think of a diminished chord as being an "even lower" minor triad.
Augmented chord = root + major third up from the root + augmented fifth up from the root. Example: C (root) + E (third) + G# (fifth). Think of an augmented chord as an "even higher" major triad.
Check out the image below to help you remember the relationships between the four types:
When labelling a chord, be sure to label it by its note name and its quality. So instead of identifying a chord as simply a "C chord," you should say that it is a "C minor chord" or what-have-you to be more precise and to avoid confusion.
Melody
Like we said, chords provide the backbone for melody. A good melody will fit harmoniously (literally and figuratively) within the chord progression—the sequence of chords in a piece of music.
More Music Theory Crash Courses
1) Introduction
Why should we learn about music theory?
2) The Very Basics
A snapshot look at the staff and note placements.
3) Intervals
All you need to know is various combinations of half-steps and whole-steps.
4) Scales
A scale is a series of ascending and descending notes. The way a
scale sounds depends on the interval relationship between the pitches.
5) Key Signatures
A key signature is a bank of either sharps (#) or flats (b) found at
the beginning of each staff to the right of the clef symbol.
