Unit 3: Music Fundamentals III: Triads and Seventh Chords

Triad and Chord Qualities

• Chord - A group of pitches that forms a single harmonic idea.
• Triad - A three-note chord made up of two intervals stacked in thirds.
• Root - The lower note of the chord.
• Third - The middle note because it’s an interval of a third above the root.
• Fifth - The upper note, it’s a fifth above the root.
• Major triads are indicated with uppercase Roman numbers.
• Minor triads are indicated with lowercase Roman numbers.
• Subtonic triad - The chord built on the seventh scale degree in natural minor. It’s a major chord, a whole step below the tonic.
• Commonly used triads from natural minor:
  • Major mediant (III)
  • VII
  • Subtonic

Seventh Chords

• Seventh chord - Contains four notes. All of them are unstable because the arrangement of tones contains an interval of a seventh.
  • Root
  • Third
  • Fifth
  • Seventh
• Five Basic Seventh Chords
  • Major seventh (major triad + major seventh)
  • Dominant seventh (major triad + minor seventh)
  • Minor seventh (minor triad + minor seventh)
  • Half-diminished seventh (diminished triad + minor seventh)
  • Fully-diminished seventh (diminished triad + diminished seventh)
• A seventh chord in first inversion has the third of the chord in the bass.
  • The root of the chord is the interval of a sixth above the bass.
  • The inversion symbol is 6/5.
• A seventh chord in second inversion has the fifth of the chord in the bass.
  • The root of the chord is the interval of a fourth above the bass, and the added seventh is a third above the bass.
  • The inversion symbol is 4/3.
• A seventh chord in third inversion has the seventh of the chord in the bass.
  • The root of the chord is a second (the inversion of a seventh) above.
  • The inversion is written as 4/2 or 2/1.
• An easy way to remember the inversions is the "Inversion Hotline”, 664-765-4342.
• The fully-diminished seventh chord (diminished triad and diminished seventh) occurs on the leading tone in harmonic minor.
• The V7 chord is the same in major and harmonic minor. It only occurs on the dominant.

Diatonic Chords

• Diatonic chords - A set of chords that are derived from the notes of a particular key. They are built using only the notes of the major or minor scale of that key. There are seven diatonic chords in each key, each one built on a different note of the scale.

Major Diatonic Chords

• The major diatonic chords are built using the notes of the major scale. They are as follows:
  • I (major)
  • ii (minor)
  • iii (minor)
  • IV (major)
  • V (major)
  • vi (minor)
  • vii° (diminished)

The I, IV, and V chords are major, while the ii, iii, and vi chords are minor. The vii° chord is diminished.

Minor Diatonic Chords

• The minor diatonic chords are built using the notes of the natural minor scale. They are as follows:
  • i (minor)
  • ii° (diminished)
  • III (major)
  • iv (minor)
  • v (minor)
  • VI (major)
  • VII (major)

The i, iv, and v chords are minor, while the III, VI, and VII chords are major. The ii° chord is diminished.

Figured Bass

• Figured bass - Consists of the bass line and the Arabic numbers under the bass line that represent the intervals above the bass to be played.

  • The voicing of the chord and the linear movement of each line is determined by the performer.

• Purpose of inversion symbols - To indicate the lowest-sounding note within a chord.

• The Arabic numbers used in inversions indicate the same thing when used as part of figured bass but the added accidentals, slashes, or plus signs that may be part of figured bass are not included in inversions.

• Chords to use when harmonizing:

  

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