Fig. 1 · A to B

interval

A major second

AlowerBupperM22 half steps

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

On the keyboard

AB
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 → Cminor third · imperfect consonanceA → C♯major third · imperfect consonanceA → Dperfect fourth · perfect consonanceA → D♯augmented fourth · dissonanceA → E♭diminished fifth · dissonanceA → Eperfect fifth · perfect consonanceA → Fminor sixth · imperfect consonanceA → F♯major sixth · imperfect consonanceA → Gminor seventh · dissonanceA → G♯major seventh · dissonance

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