Here’s Nate again, this time with a lesson on building chords in the key of G Major.  From the last lesson on scales and the circle of fifths, you’ll remember that the key of G Major has one sharp: F#.  So the scale runs as follows: G-A-B-C-D-E-F#-G.

The most basic chord is a triad, which consists of three notes stacked in thirds.  To build a Major chord, start with a major 3rd, then stack a minor third on top.  The G Major chord is a triad consisting of notes G, B, and D.  G to B is a major 3rd, and B to D is a minor 3rd.  In the lesson you’ll see that you can build chords by playing every other note in a scale.

Moving up a whole step and playing A, C, and E simultaneously produces an A minor chord. As you approach the top of the scale, extend it another octave to fill out the chords. For example, to form a D Major chord, you would press D (skip E), F# (skip G), and A.

Now for the good stuff. Take what you learned and move it down to C. Starting with notes 1, 3, and 5 (C-E-G), move the shape up the keyboard until you reach the C Major chord one octave higher. By playing every other note on just the white keys, you will play the following chord progression: C Major, D minor, E minor, F Major, G Major, A minor, and B diminished.

This progression of Major, minor, and diminished chords is the same for every major scale. The chords are often referred to by their position in the scale, and indicated by the corresponding Roman numeral.

Chord Symbols, Chords, Scale Degrees, Notes and Intervals in the Key of C Major

Roman numeral I ii iii IV V vi vii°
Chords C D minor E minor F G A minor B dim
Scale degrees
tonic supertonic mediant subdominant dominant submediant leading tone
Scale Notes
C D E F G A B
Interval from C
Perfect
unison
Major
2nd
Major
3rd
Perfect
4th
Perfect
5th
Major
6th
Major
7th

Harmony in Western music relies mainly on the primary triads: those built on the tonic (I), subdominant (VI), and dominant (V) scale degrees noted above.  The chords themselves are often referred to by the Roman numerals I, IV, and V, which in the key of C would be C Major, F Major, and G Major.

While it’s not important to immediately memorize all of the names and nuances of notation, it is critical to understand the relationships between keys, chords, and scale degrees.  Just knowing I, IV, V will take you a long way, since most popluar music is based on these three chords, sometimes with one or two others mixed in.  Once you are comfortable building chords in common keys, it’s time to move on to chord progressions.