Chords are created using guitar scales. Each chord is made out of a major (or minor) scale, depending on the key. So an A Major chord will be made from the A major scale, while an F Minor chord will be made using an F Minor scale. Each scale starts on a 1st note, the root note. If the scale is in the key of F, it will start on an F note. Starting on this root note, the scales take two seperate paths - major and minor. The basic major scale starts on the root note then will go up a whole step to the 2nd note, then another whole step to the 3rd note, then a half step to the 4th note, then a whole step to the 5th note, then a whole step to the 6th note, then a whole step to the 7th note, and finally a half step back to the root note. So a major scale will look like this in term of notes: 1, 2, 3, 4, 5, 6, 7, 1
A major chord is created out of the 1st note, the 3rd note and the 5th note. For an example, lets look at the A Major chord.
The A major scale in terms of note names looks like this: A, B, C#, D, E, F#, G#, A Using our rule on how to crate a major scale we can see that A is the root note, B is the 2nd note, C# is the 3rd note, D is the 4th note, E is the 5th note, F# is the 6th note, G# is the 7th note and A is the root note. Looking back a our A major chord we can see that the notes used are A, C# and E - and if we look at our scale, those are the 1st note, the 3rd note and the 5th note!
With the Major chord out of the way, we can now look at the minor chord. Notice how there is only one note difference between the major and the minor chord. The difference is that the 3rd note turns into a Flat 3rd note. This rule also applies to the scale - the only difference between the major and the minor scale is that the 3rd note in the major scale will be replaced by a flat 3rd note in the minor scale. And the minor chord constructed will consist of the root note, the flat 3rd note and the 5th note. The A minor scale consists of A (the root note), B the second note, C the flat 3rd note, D the 4th note, E the 5th note, F# the 6th note, G# the 7th note and back to A, the root note.
So using the rule for creating the minor scale, we can see that the A minor chord will be constructed of an A note, a C note and an E note.
When these three notes are shown on a chord diagram we can see that what is created is in fact the A minor chord.
These two scales can be applied to any key, remembering that the scale will always start on the root note and then using the rule shown at the start, switch between the 2nd note, 3rd note, 4th note etc. and to create the minor scale, we simply flatten the 3rd note. Now you can enjoy creating your own chords!
Starting off with major 7th chords. Normal major chords consist of the root note, the 3rd note and the 5th note. What major 7th chords do is replace the root note with a 7th note. There is a very simple way to do this rather than trying to work out what the 7th note in a scale is. All you have to do is flatten the root note in a major chord. It really is that simple! For examjple lets take an A major which looks like this: 002220. To create an Amaj7, we flatten the root note which will make the chord look like this: 002120. The same rule applies to any other chord - lets take a D major for an example which looks like this: 000232. Once we flatten the root note to create a maj 7, the chord will now look like this: 000222. This is of course not the only way to create a maj7, but by far the simplest.
Minor 7th chords are created similarly but not quite the same. The only difference is that we start with the minor chords and change the root note a whole tone down rather than a semitone. So a Dm which looks like this: 000231 will change to the Dm7 and look like this: 000211. We can see a similar change in the Am chord (002210) when it also changes to the Am7 (002010). Like with maj7 chords, there are other ways of creating m7 chords, but this method is by far the easiest.
This brings to the final 7th chord that we will be looking at: the dominant 7th chord. This chord is slightly like a mixture of the previous 2. It is made from a major chord, but the root note is taken a whole tone down rather than a semitone. So a D7 will change from 000232 to 000212. An A7 will change from 002220 to 002020. An E7 will change from 022100 to 020100 and the list goes on.
These chords are alternate options to normal chords and are neutral - netither major nor minor. They are created by replacing the 3rd or the flat 3rd note with either a 2nd or a 4th depending on whether the chord is sus2 or sus4.
First of all lets look at the sus2 chord. Lets take D as an example which looks like this 000232 or if its aminor, then this 000231. But that doesn't matter. Because the 3rd note is being completely replaced. In the Dmaj, the 3rd note must be taken down a whole tone to get to a 2nd note so it will change from 000232 to 000230. This is also the chord that will appear when creating it out of a minor, because the flat third note only needs to go down a semitone.
For the sus4, we can also use D as an example. To get the third note to the 4th, we need to raise it a semitone, since the 3rd note does not have a sharp. When changing it from a flat 3rd, we need to bring it up a whole tone. So no matter whether we're using a D major or a D minor Dsus4 will look like this: 000233 I can show this again using the A chord. A major looks like this 002220. When the third note is sharpened to a 4th, it will now look like this:002230. To get from an A minor (002210) we need to bring the flat 3rd up a whole tone, also resulting in 002230.