My name is Manuel Diewald and I am a Sydney-based guitar teacher in West Pennant Hills with a B.Mus. (Hons) (First) in Music Pedagogy from The University of New South Wales (UNSW).
Understanding what notes a chord is made up of can be very helpful when reading and understanding music whether that is reading off of sheet music or playing from a chord chart. This understanding allows a guitarist to easily navigate through the harmony (chord structure) of a piece or song. It means that you are at an advantage when reading a piece or a chord chart in a certain key as you will understand what common chords will be used before you start playing the piece or song. Another way this is useful is when jamming or improvising for the same reasons. Simply, we are going to start at looking at a scale, and then from that scale, we will build our chords.
Scales. Here lies the first building block to understanding chords. We will look at the Major and Minor scales in these examples. To find either a major or minor scale we need to look at the formula for these. Don't feel to overwhelmed, this formula is good to know but ultimately you will just remember what notes a scale is made up of rather than having to continuously go through these formulas. The two main intervals (distance between notes) we will talk about are Semi-tones (the distance of 1 fret on the guitar) and Tones (the distance of 2 frets on the guitar).
T - T - ST - T - T - T - ST. If we take this formula starting with C we get the notes C - D - E - F - G - A - B - C
Each note in a scale is a degree of that scale. For example, C is the 1st degree, D is the 2nd degree, E is the 3rd degree, and so on.
Triad. A triad is what a chord is made up of and simply, a triad is when you take the 1st, 3rd, and 5th degree of the starting note in a scale (I - III - V or 1 - 3 - 5).
Let's begin with C being the 1st degree we then take the 3rd which is E and then the 5th which is G and when we put those 3 notes together we get a C major triad or C major chord C - E - G. Now if we start with D being the first degree within C major we take the 3rd degree from D which is F and the 5th degree from D which is A creating a D minor chord, D - F - A. Now you might wonder why is C a major chord and D a minor chord. Here we have to look at what quality (quality being Major or Minor) a degree is in a Major scale.
diminished (I will cover this in another Blog)
So if we take all this information and find the triad from each degree we have:
C Major C - E - G
D minor D - F - A
E minor E - G - B
F Major F - A - C
G Major G - B - D
A minor A - C - E
B diminished B - D - F (not commonly used)
I will go over the minor scale now but I will run through it a little quicker as the ideas of the Major scale stay the same, only the formula changes.
T - ST - T - T - ST - T - T. If we start from A we get the notes A - B - C - D - E - F - G - A
When we look at the quality of each degree, we need to alter the 5th degree, also known as the dominant, as the dominant is always Major. There are exceptions to this rule and composers and songwriters break the rules which is absolutely fine but it is important to understand this. If we use the notes within A minor scale then technically the 5th degree is a minor triad but since the dominant is Major we will alter it. Using only the given notes within a scale and not altering them is called the 'Diatonic' notes.
The quality of each degree in a minor scale is:
minor A - C - E
diminished B - D - F
Major C - E - G
minor D - F - A
Major E - G# - B (Diatonic would be minor E - G - B)
Major F - A - C
Major G - B - D
As you may have noticed, C Major and A minor share the same notes and chords (apart from the altered 5th degree of the minor scale to create a Dominant chord).
This may seem like a lot of information at first but what I suggest to do is go through it slowly and take your own notes. Writing this information down on your own can help retain the information a bit better than just reading it. Then I would suggest going through all the chords (you can omit the diminished chords if you are having trouble with finding that chord) of each scale to give you a better idea of what chords could potentially be used in each Key Signature. The Key Signature simply represents the notes of the scale. For example, you could either be in the key of C Major or A minor.