piano scale
F Mixolydian
F1G2A3B♭4C5D6E♭♭7
Major with a flattened seventh: the scale that fits a dominant seventh chord without altering it.
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
FWGWAHB♭WCWDHE♭WF
What is true of it
F Mixolydian is F, G, A, B♭, C, D and E♭, and back to F.
Its steps are W – W – H – W – W – H – W, where W is a whole step and H a half.
On the same tonic, F major 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.