This is from the Theory Section on Chords. Here we extend the harmonized C major scale to generate seventh chords. Go to the associated article to read more.

Here we play through each of the generated chords in the open position. These are:

C major Scale: C D E F G A B C (D E F G A B C etc - extend through octaves)

C - E - G - B = C Major Seventh (Cmaj7)
D - F - A - C = D Minor Seventh (Dm7)
E - G - B - D = E Minor Seventh (Em7)
F - A - C - E = F Major Seventh (Fmaj7)
G - B - D - F = G Dominant Seventh (G7)
A - C - E - G = A Minor Seventh (Am7)
B - D - F - A = B Half-Diminished (Bø7)
C - E - G - C = C Major Seventh (Cmaj7)

Notice for the last chord, we don't play the 7th chord, but just the standard C major triad C - E - G = C Major (Cmaj). We've already started with the C maj7 and don't need to do it again. Besides, it is nice to revert to the C major chord after a string of 7th chords. Notice how it sounds more resolved than the 7th chords.

It is useful to end on the root chord triad whenever using lots of extended chords in your own music. It brings resolution (completes) the piece by returning the foundation root chord of the key (C major in this case). By contrast, 7th chords are less stable than triads, so this transition works well.

Traditionally, moving from the V7 chord (G7 in this case) to the I (root) chord gives the strongest form of chord resolution in Western Tonal music.