In total, there are 12 major scales because the major scale pattern can begin on any of the 12 notes of the musical alphabet.
There are 3 minor scales, or more precisely, 3 variants of the minor scale because of how harmony and melody interact in tonal music. Composers change some notes of the minor scale to achieve a specific sound for a particular style.
There are two ways to tell whether a song is major or minor: by ear and by sight. When doing it by ear, listen to the major vs. minor qualities in the music. When reading the sheet music, the answer is in the key signature and in notes and chords are used.
No, not every song has a chorus. While most songs do have a chorus, there are plenty of great songs without one. These songs are just as effective and prove that is not necessary for a song to have a chorus.
No, the tonic is not the same as the root. While the tonic is the fundamental, ‘home’ note of scales and keys, the root is the fundamental note of chords and arpeggios.
‘Tension and release’ refers to the build-up of musical intensity that eventually dissolves and relaxes. For the listener, a moment of unrest in the music creates an expectation for its resolution and an anticipation for the drama to resolve. Tension and release keeps the music moving forward.
The cadential 6 4 is a melodic and harmonic formula that often appears at the end of phrases in music of the common practice period. Typically, it consists of a decoration of the dominant chord by displacing both its third and fifth by a step above.
This short, fun video from medici.tv went viral some time ago. It features the Hungarian conductor Iván Fischer criticizing the well-known tune. “I think it’s a very poor melody” he says, “it’s not written well” and then goes on to recompose it.