Points to Remember:
• Triads are 3-note chords; seventh chords add one more note (4 notes).
• There are 3 main kinds of 7th chords: Major 7, Minor 7 and Dominant 7.
• There are 2 kinds of 3rds (major and minor), and 2 kinds of 7ths (major 7 and flat 7). Major 3rds makes a chord 'bright/happy;' minor 3rds are 'dark/sad.' Major 7s are 'pretty;' flat 7s are 'bluesy/funky.'
• The 3rd and 7th are the 2 most important notes in the chord. They give it its essential character.
• Diatonic 7th chords:
Maj7 min7 min7 Maj7 Dom7 min7 min7(b5)
I 7 ii7 iii7 IV7 V7 vi7 viiØ7
( Ø = half diminished )
• Close voicings (1-3-5-7), are very easy to play on piano, but difficult-to-impossible on guitar.
• Major 7 chord gets its name because it has the 7 from a major scale.
• Dominant 7 chord (V7 chord) gets its name because, besides the tonic (I chord), it's the most important/strongest. It gravitates strongly back to the tonic chord.
• 2-5-1 chord progressions are common in music and contain one of each 'chord family' (my term).