The key of A minor
A B C D E F G
No sharps or flats. Relative major: The key of C major.
The triads of the key
i
Am | ii°
B° | III
C | iv
Dm | v
Em | VI
F | VII
G |
The seventh chords
i7
Am7 | iiø7
Bm7♭5 | IIImaj7
Cmaj7 | iv7
Dm7 | v7
Em7 | VImaj7
Fmaj7 | VII7
G7 |
In practice the V of a minor key is almost always major, taken from the harmonic minor: E7 (V7), which carries the leading tone G♯.
A natural minor scale
Open it in the app: 6. Harmony, in A