The composition of chords

Chords are groups of notes that are sounded together. The notes are said to be in harmony, meaning simply that the total sound produced by the combination of notes is at least arguably a pleasing one. Harmony may consist of as few as two notes. Most commonly chords are made of three or four. A certain few of these 3- and 4-note chords are appropriate for accompanying traditional music as represented in Dear Old Illinois and are the ones of concern to us here and now.

The chords we will be examining are of three different types, major, minor, and seventh. These are among the simplest of chord types.

The major chord

First, let's look at the major scale, also known as the diatonic scale or the "do-re-mi-fa-sol-la-ti-do" scale. Here is that scale in the key of C.

The major chord is made from the 1, 3, and 5 notes of the major scale. This is true for any key. Here is that chord in C, the C major chord. It is made from the notes 1 (C), 3 (E), and 5 (G). Let's see and hear it.

It was stated above that the chords we will be examining are made of either three or four notes, and you can see that the C major chord is made of three. To clarify, this means the chord is made from notes of three different letter names. The actual number of notes can be more, as long as they are all either C, E, or G notes. The example below has more notes than the one above, but it is still just a C major chord.

Here is how this relates to the guitar. The notes made by playing a C chord are shown at the bottom. They are all either C, E, or G.

For the sake of comparison, here is the same look at the D major chord. First, the D major scale.

The major chord is made from the 1, 3, and 5 notes of the major scale. Again, this is true for any key. Here is the D major chord.

The minor chord

In the examples above, the distance from the 1 note to the 3 note is called a major 3rd interval. If we flat the 3 note by one half-pitch, the distance from the 1 note to the flatted 3 note is a minor 3rd interval. If we combine the 1, flatted 3, and 5 notes, we have a minor chord. Let's see and hear the C minor chord.

And as above, there can be any number of notes in a C minor chord, so long as all of them are either C, E♭, or G. Here is an expanded C minor chord.

The 7 (or 7th or seventh) chord

The 7th chord is formed by adding another note to a major chord. The additional note is a flatted 7 note. In the case of the C7 chord, this is a B♭ note.

And again, there can be any number of notes in a C7 chord, so long as all of them are either C, E, G, or B♭. Here is an expanded C7 chord.

This covers the structures of all of the chord types used for accompanying the music of Dear Old Illinois. Below is a chart which gives the notes that compose the guitar chords used in the book.

Chord composition chart

Chord	1	3	5	7
B7	B	D#	F#	A
E	E	G#	B
A	A	C#	E
D	D	F#	A
G	G	B	D
C	C	E	G
F	F	A	C
Em	E	G	B
Am	A	C	E
Dm	D	F	A