Chords in the minor mode · The chords of a key · Music theory
In minor the leading tone is used (the harmonic scale) and the qualities change. I and IV are minor; V and VI, major; II and VII, diminished, and III,…
Chords in the minor mode
In minor the leading tone is used (the harmonic scale) and the qualities change. I and IV are minor; V and VI, major; II and VII, diminished, and III, augmented.
The major V, with the leading tone, is what gives the minor mode its dominant. Without it V would be minor and would not have the same pull back to the tonic.
The other possible notes
The table of chords from the harmonic minor is only the starting point, because the minor mode has movable notes. With natural VII you get a major VII (G–B–D in A minor) and a major III (C–E–G), both very common, the latter being the relative key. With raised VI you get a major IV and a minor II, above all in rising melodic lines.
The augmented III of the table is in fact rare in practice: the normal one is the major III, with natural VII.