The supertonic of any scale is the second degree of the scale. Therefore, the supertonic of C major is D.
The supertonic triad in the key of A flat major is B flat, D flat, and F natural
G
E
B flat
G
F is the tonic. Therefore, from supertonic (the second note) to supertonic is G, A flat, B flat, C, D flat, E natural (a harmonic minor scale has the 7th note raised), F, G.
Tonic, supertonic, mediant, subdominant, dominant, submediant, leading note, tonic again..
Tonic, supertonic, mediant, subdominant, dominant, submediant, leading note, tonic again..
In ascending order, the names for each scale degree are the tonic, supertonic, mediant, subdominant, dominant, submediant, leading tone, and the tonic again.
If C is the tonic, D is the supertonic.
In the perspective of European-descendent theory, the degrees of any key or scale (major, minor, or modal) can be classified as follows: 1 - Tonic 2 - Supertonic 3 - Mediant 4 - Subdominant 5 - Dominant 6 - Submediant 7 - Leading Tone Let us take the case of C major as our key/scale: C - Tonic D - Supertonic E - Mediant F - Subdominant G - Dominant A - Submediant B - Leading Tone Similarily, this works in the minor keys, too. Using A natural harmonic as our key/scale: A - Tonic B - Supertonic C - Mediant D - Subdominant E - Dominant F - Submediant G - Leading Tone