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Triads in practice

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In this section we meet more triads of different types, in different keys, and in different configurations!

The triad

Previously, in Introduction to harmony, we learnt about triads and and how they are constructed. Here's a quick reminder:

Creating a triad of I in C majorCreating a triad of I in C major

Major and minor

Just as in scales, keys, and intervals, we have can have a major triad and a minor triad. So far, we have only met major triads.

You can tell a major triad apart from a minor one by the distance from the root to the third. In major triads, this interval is a major third (four semitones), and in minor triads it is a minor third (three semitones).

In C major, the distance between C and E is a major third. Look at the example to check that the same is true of G major and F major:

Major thirds in the triads of I in C major, G major, and F majorMajor thirds in the triads of I in C major, G major, and F major

Let's have a look at creating a triad on I in the minor keys with the same key signatures - A minor, E minor, and D minor, and look at the interval between the bottom two notes:

Major thirds in the triads of I in A minor, E minor, and D minorMinor thirds in the triads of I in A minor, E minor, and D minor


This is so far quite simple, but notice that both major and minor triads have both type of third, major and minor!

In a C major triad, the interval between C and E is a major 3rd, but between E and G is a minor 3rd. On the other hand, in an A minor triad, the interval between A and C is a minor third, but the interval between C and E is a major 3rd.

In both cases, the outer notes (1 and 5) are the same: a perfect fifth.

What's happening is the simple sum: "a minor 3rd + a major 3rd = a perfect 5th". Whether the major or minor 3rd comes first doesn't matter, you will still span a 5th.

The very important thing to remember, however, is that the triad is defined as major or minor on the basis of the interval between the root and the third, and not between the third and the fifth.

Naming minor chords

We name minor chords and triads in almost the same way as we do for major chords and triads. If we represent C major just as a C chord, then the equivalent for C minor is Cm - we add a little (lower case) "m" to show that it is a minor chord.

We also use lower case when using Roman numerals for a triad in a minor key. As you can see in the example above, we refer to a triad of i in A minor. Any minor triad uses a lower case Roman numeral, and any major triad uses an upper case Roman numeral.

Triads in other keys

All of this is just the same in every major and minor key. Here are some triads on the tonic in some other keys:

Major and minor tonic triads in some other keysMajor and minor tonic triads in some other keys

Broken chords

In the Introduction to harmony, we found that harmony does not always have to consist of notes occurring at the same time. Arpeggios can be considered harmony, because the notes belong to the same triad, even though they come one after the other.

This idea can apply to other patterns of notes. You may have heard the terms broken chord, or Alberti bass, particularly if you play the piano. Both of these are used to provide harmony without having notes sounding at the same time.

Broken chords

A broken chord refers to exactly this principle of playing the notes of a chord not together but separately. It may be helpful to think of the notes of the chord as having been "broken apart" from each other.

We can also say that an arpeggio is a kind of broken chord.

Alberti bass

The Alberti bass is a particular style of broken chord used for accompaniment, and is a particular cliché in Classical piano pieces.

The basic note pattern of the Alberti bass is: lowest note, highest note, middle note, highest note followed by the lowest note to start the pattern again. There is an Alberti bass pattern in the lower part of the following example by Mozart:

An Alberti bass in music by MozartAn Alberti bass in music by Mozart

Notice that both hands in this music for piano are written in the treble clef! You can clearly see the outline of a triad on I in the first bar, using the "Alberti bass" pattern.

Contrary and similar motion

There are two more terms that describe the movement of notes which we'll mention here: contrary motion and similar motion.

These terms refer to the direction in which two different parts in a piece of music are headed: up or down. When two parts move in the same direction, they have similar motion, and when they move in the opposite direction to each other, they have contrary motion.

This can apply to the movement of the notes of broken chords. Here is an example in which bar 1 has the two parts in contrary motion, and bar 2 has the two parts in similar motion:

Contrary motion in bar 1 and similar motion in bar 2Contrary motion in bar 1 and similar motion in bar 2


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