Fig. 1 · Ab to Bb

interval

A♭ major second

A♭lowerB♭upperM22 half steps

A whole step. The distance between most neighbouring notes of a major scale.

On the keyboard

AbBb
Fig. 2

What is true of it

A♭ up a major second is B♭: 2 half steps, and 2 letters counting both ends.

Turn it upside down — put the A♭ on top — and it becomes a minor seventh. The two numbers always add to nine, and the two sizes to twelve.

It is a dissonance.

Every interval on A♭

A♭ → B♭♭minor second · dissonanceA♭ → C♭minor third · imperfect consonanceA♭ → Cmajor third · imperfect consonanceA♭ → D♭perfect fourth · perfect consonanceA♭ → Daugmented fourth · dissonanceA♭ → E♭♭diminished fifth · dissonanceA♭ → E♭perfect fifth · perfect consonanceA♭ → F♭minor sixth · imperfect consonanceA♭ → Fmajor sixth · imperfect consonanceA♭ → G♭minor seventh · dissonanceA♭ → Gmajor seventh · dissonance

C M2C♯ M2D♭ M2D M2D♯ M2E♭ M2E M2F M2all 204