Basic Music Theory (Keys)

I recently had a student ask what it means when you say things like "it's in the key of G" or "it's in the key of B Flat" or other such music terminology. I'll try to explain.

The first thing about this business of KEYS is related to the major scale. You need to understand it first. I've already covered this topic a few posts back. You can link to it here:

http://www.perfectnotes.blogspot.com/2009/11/basic-music-theory.html

So hopefully now you understand that there's this collection of tones called the major scale. It might help to listen to it a few times to get really acquainted with it. Now let's look at the KEY of C Major.

Imagine that a musical key is like a little Solar System and C is the sun. All the chords in the key of C revolve around it like planets around the sun. The C Major chord is the center of this little universe. A childish comparison perhaps but I think it's apt. Check this out.

Here are the notes and chords in the key of C Major.

• CEG = C Major Chord
• DFA = d Minor Chord
• EGB = e Minor Chord
• FAC = F Major Chord
• GBD = G Major Chord
• ACE = a Minor chord
  
• BDF = B diminished chord

Hopefully you can see the logic behind the notes of the scale. They're somewhat alphabetical:

C, D, E, F, G, A, B, C

Remember that there's only 7 tones in the major scale, it starts over again at the next C. That tonal "distance" is called an Octave for 8 (of course.)

Now that we know the tones we can assign a placement for each of the tones, numerically. In the context of KEY the letter C can refer to both the individual note C as well as the the 3 note family CEG that refers to the C major chord. Technically speaking it is often called the root note or Tonic with the F being the Subdominant and the G being the Dominant.

Don't worry to much about that though. Here's the list:

• C = 1 (root)
  
• D = 2
• E = 3
• F = 4 (sub dominant)
  
• G = 5 (dominant)
  
• A = 6 (relative minor)
  
• B = 7

From now on when you refer to a C chord (in the key of C ) you can refer to it as the 1 chord. And the F chord as the 4 chord, and the G chord as the 5 chord. It's often written as Roman numerals but for now I'll stick with regular numbers. These three chords hold a very important musical relationship. Literally millions of songs have been written using just these 3 chords. Great songs. I don't mean C, F, and G. I mean the 1, 4, and 5 chords. That relationship is the same for any key. Here's a great link for a list of songs you might know using the 1, 4, and 5 chords of a given key.

http://newsgroups.derkeiler.com/Archive/Alt/alt.guitar.beginner/2006-08/msg01170.html

So, just as we can create a major scale in the Key of G. We can assign the number value and tonal placement for the Key of G.

• G = 1
• A = 2
• B = 3
• C = 4
  
• D = 5
• E = 6
• F# = 7

The 1, 4, 5 chords are G, C, D.

The key is what gives a song a tonal center (or lack of) and helps the musician understand the relationship of the the tones within that key. In in my next post I'll go into some more detail about these relationships.

Hope it helps.
Chum