piano scale
C Dorian
C1D2E♭♭3F4G5A6B♭♭7
Minor with a natural sixth. The second mode of the major scale.
Written out
Every accidental is written in, rather than left to a key signature, so the letters can be read one at a time.
The step pattern
CWDHE♭WFWGWAHB♭WC
What is true of it
C Dorian is C, D, E♭, F, G, A and B♭, and back to C.
Its steps are W – H – W – W – W – H – W, where W is a whole step and H a half.
On the same tonic, C natural minor differs from it by exactly one note.
Chords made only of these notes
Found by testing every chord in the catalogue against these 7 sounds, not chosen.