music theory basics

Music Theory Basics

Chords

In this section on basics we will deal only with tertian harmony. That means chords built in thirds. The first, and most important category of these is triads. A triad has 3 notes and it is built by stacking one third on top of another. The lowest note, which gives the triad it's name, is the root, the next note is the third, and the next note is the fifth. They get these names because the third of the chord is a third above the root, while the fifth is a fifth above the root.

There are 4 basic qualities a triad can have. They are major, minor, augmented, and diminished. A triads basic quality is determined by the typed of thirds (major or minor) are used, and their position in the triad.

Major

Major triads are made up of a major third between the root and third, and a minor third between the third and fifth. Below are a few examples of major chords.

Minor

Minor triads also have one of each kind of third, but their minor third is on the bottom (between root and third), with a major third between the third and fifth. Notice that this gives the same total number of half steps between root and fifth, so both major an minor triads have a perfect fifth between the root and the fifth. In the example below minor triads have been built on the same roots used in the previous example for major triads.

Augmented

Augmented triads are made up of 2 major thirds. This means one more half step between the root and the fifth than is found in major and minor chords, making an augmented fifth.

Diminished

Diminished triads are made up of 2 minor thirds. This means one less half step between the root and the fifth than is found in major and minor chords, making a diminished fifth.

Chords within a Key

Because it is the pattern of half steps and whole steps that defines a scale, the interval between any 2 scale degrees will be the same in any key. Therefore, within any major key the chords built on the same scale degree will have the same quality. The example below shows all the triads in C major with their qualities. (M = major, m = minor, A = augmented, d = diminished)

Roman numerals are commonly used to designate these chords in tonal music. With large case letters used for major and augmented triads, and small case letters used for minor and diminished. The chords in the previous example would be numbered like this:

[ Roman Numerals for Triads in C Major ]

These example show C major. The qualities and numbers would be the same for any scale starting on the first scale degree. So in the key of D major I would be spelled d- f#-a instead of c-e-g.

Chords Worksheet

Scale degrees refer to a notes place in the scale. The first scale degree is the first note you play in an ascending scale, the second note is the second scale degree and so on. Scale degrees are commonly notated as a number with a carot over them like this -

.Therefore a triad built of the first scale degree would have

and

in it, while a triad built on the second scale degree would have

, and

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