All chords belong to groups in keys.
How to figure out where they all come from. [Intermediate Beginner Lesson]
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This article will hopefully simplify the understanding of chords belonging to groups and their corresponding placements in keys. Even basic music theory can be a little daunting for some. I have taken the time to do three excel charts (see below), to help you see how all chords, major and minor, all belong to one another and how they relate to one another in figuring out chord usage and availability in music.
Intermediate Beginner Lesson
Chords in Keys
For the sake of simplicity, we will only use the basic twelve keys in music applied to the guitar. (Yes, mathematically, there are more than twelve keys). As you can see (first chart), I have color-coated the chords in the charts below in order to give you a better "visual" understanding of comparing chords and their placements in keys.
This first chart shows the names of the keys in the far left column: C through F. At the top of the chart, you will see "Major", "minor" and upper and lower-case Roman numerals. The Major (upper-case) numerals are "I, IV and V", while the minor (lower-case) numerals are "ii, iii and vi".
In the middle of the chart, you can see six of the chords in each key, reading left to right in the row corresponding to the key. I did not include the diminished (vii°) in these charts, as we are only interested in the basic theory behind Major and minor chords and their placements in keys.
At the bottom left of the chart, we have the "Enharmonic" notes. These are notes that are single notes with dual names. They are color-coated to correspond with the chart to help you understand their placements.
Reading the chart
Let's take a look at the key of C Major (yellow). As you can see, the three Major and three minor chords in the key of C Major are C, Dm, Em, F, G and Am.
Now let's take a look at the next key, G Major (light green). If you notice, you will see that four of the chords in the key of C Major also exist in the key of G Major, however, their (Roman numerical) placements in each key are different. Now, take a look at the bottom of the chart for the key of F Major. Again, four of the chords in the key of C Major also exist in the key of F Major, but in different placements.
So, suffice it to say, the "C Major" chord belongs in three different keys. "D minor" also belongs in three different keys. In fact, all of the chords belong in three different keys. All of the Major chords belong in the (Roman numerical) placements of the I, IV and V. All of the minor chords belong in the (Roman numerical) placements of the "ii, iii and vi".
So, how is this useful information?
Let's say that you hear a song that you like and want to learn how to play on your guitar. Normally, you would probably have immediate access to the internet and could easily find the chords to that song online.
What if you don't have internet access because you're out camping or at the beach with your friends, and your internet connection is very poor. How are you going to learn this song?
Maybe you’ve already decided that the song is fairly easy and you could probably figure out two or three of the chords, but you have no idea what the other chords are in the song. How are you going to figure out which chords are the right chords?
You can apply the process of elimination!
The chords you have already figured out are "A and E", but there's two other mysterious chords in the progression. You think that one of them is a minor chord, but you're not sure. The other one, sounds like it's major, but again, you're not sure.
Okay, so let's look at the chart (above) to find the chords "A" and "E". Well, "A" and "E" are both in the key of A Major and E Major. But, do they exist in any of the other keys?
Now, we apply the process of elimination. In the key of A Major, A is the key chord or the "I". In the key of E Major, A is the "IV". A Major also exists in the key of D as the "V", but E Major is not in the key of D. So, now, it looks like our only two choices are the key of "A" and the key of "E". We've eliminated any other possible keys.
Our next step
We need to listen to the song again and try to figure out all three of the Major chords in both the key of "A" and the key of "E". Let's start off with the key of "A". The three chords we have available according to the chart are: "A, D and E" Well, we already know that both A and E are in the song.
Question is, does the D Major chord exist in this song? Hmm, okay, so we've listened to it again and for some reason "D" doesn't seem to fit in the song. So, again, using the process of elimination, we now have to assume that the other Major chord comes from the key of "E". That chord must be the "B major" chord. We play the song again and try the "B" chord against the progression, and it works!
Now we know for sure that the song is in the key of "E". But, what about the other chord? According to the chart, the other mystery chord must be a minor - but, which one is it? After careful analysis and trial and error of all three minor chords in E, it was determined that the last chord in the song was the "F# minor" chord. Now, we've figured out by applying the process of elimination that the chords for this song are "E, A, B and F#m".
Major chords.
In this next diagram, we can see all of the Major chords in each of the twelve keys. At the top of the chart, we can see the Major Roman numeral positions: "I, IV and V". The "I" is the key itself. In other words, "C" is the first chord in the key of "C", "G" is the first chord in the key of "G", and so on.
Next we have the "IV" and the "V" positions.
Looking at the "C" chord, we can see that "C" is the "IV" of "G". Next to that, we have "F". So, "C" is the "V" in the key of "F". The Roman numeral placement at the top of the chart shows the position of the chord in that key. Let's try another.
Let's go down to the key of "E" (light blue). We can see that "E" is the "I" in its own key. Next to it is "B". "B" is in the "IV" column, which means that "E" is the "IV" of "B". In the key of "A", "E" is the "V".
Every Major chord belongs in three keys as either the "I", the "IV" or the "V", depending on which key it is in.
Minor chords.
The minor chord chart (below), is read just like the Major chart above, except that we won't be using the minor key reference. Instead, we can simply look at the name of the chord in the far left column and move to the right in that row to find out which minor Roman numerical position that chord is in, in that key.
For example, the first chord in the chart is "Cm". C minor is the "ii" chord in the key of Bb, it is the "iii" chord in the key of Ab, and the "vi" chord in the key of Eb.
Like Major chords, every minor chord also exists in three different keys as either the "ii", the "iii" or the "vi", depending on which key it is in.
Why do you need to know this stuff?
Songwriters and musicians use this type of basic music theory as common knowledge everyday. Yes, it is very much like learning a new language, but when you look at the above three charts as "tools'', they should help simplify solving the mysteries of why specific chords are in specific progressions in all songs. These charts can help you write songs as they show you what you have available in a key. Knowing the chords you have available in every key will help you figure out chord progressions to songs more easily and efficiently.
If you have any questions, please feel free to comment below.
