Introduction Diatonic chords

Major and Minor Keys

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  Diatonic chords: most chords in tonal music are made up of notes from the scale on which the passage is based
  
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  Altered/Chromatic
  

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  Triads may be constructed using any degree of the major scale as the root
  
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  Diatonic triads will consist only of notes belonging to the scale
  
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  Roman numerals are used to distinguish the triads (I, ii, iii, IV, V, vi, vii^o )
  
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    Major: Uppercase
    
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    Minor: Lowercase
    
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    Diminished: Lowercase with a ^o
    
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    Augmented: Uppercase with a ⁺
    
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  C major: I ii iii IV V vi vii^o
  
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  Common Diatonic Triads in major
  
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    Major: I, IV, V
    
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    Minor: ii, iii, vi
    
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    Diminished: vii^o
    
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    Augmented: none
    

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  It is a misconception that tonal music composers had three independent minor scale forms from which to choose (natural, harmonic, melodic)
  
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  6^th and 7^th degree are variable
  
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  Two versions of 6^th and 7^th degree, and both versions will usually appear in a piece in the minor mode
  
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  The most graceful thing for raised ↑6^th and ↑7^th degree to do is to ascend by step
  
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  Lowered ↓6^th and↓7^th degree tend naturally to descend by step
  
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  Refer to Example 4-3, 4-4, 4-5
  

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  The construction of triads is somewhat more involved in the minor mode because 6^th and 7^th are variable
  
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  Nearly all triads contain 6^th and 7^th, more diatonic triads are possible in minor
  
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  i, ii^o, ii, III, III⁺, iv, IV, v, V, VI, #vi^o, VII, vii^O
  
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  Common Diatonic Triads in minor
  
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    Major: III, V, VI
    
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    Minor: i, iv
    
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    Diminished: ii^o, vii^o
    
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    Augmented: none
    

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  Roman-numeral system for seventh chords: Seventh-chord type
  
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    Major seventh: M7 (e.g. IM7)
    
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    Major-minor seventh (Dominant seventh): Uppercase7 (e.g. V7)
    
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    Minor seventh: Lowercase7 (e.g. vi7)
    
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    Half-diminished seventh: Lowercase with ^ø7 (e.g. ii ^ø7)
    
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    Diminished seventh: Lowercase with ^o7 (vii^o7)
    
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  Diatonic seventh chords in Major
  
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    M7: I^M7 and IV^M7
    
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    Mm7: V⁷
    
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    M7: ii⁷, iii⁷, and vi⁷
    
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    ^ø7: vii ^ø7
    
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    ^o7: none
    

Diatonic Seventh Chords in Minor

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  Because of the variability of 6^th and 7^th degree, there are 16 possible diatonic seventh chords in minor
  
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  Common diatonic seventh chords in minor
  
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    M7: III^M7 and VI^M7
    
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    Mm7: V⁷
    
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    M7: i⁷ and iv⁷
    
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    ^ø7: ii ^ø7
    
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    ^o7: vii ^o7