In a cadence (2 part) will the upper note always be the last note? For example, I have to write GBD for chord V (C major). So the bass will have G but will the top part have a B or a D?
No. It could be any note in the harmony: G, B, or D.
Also, when writing Roman numerals for chords, should I write this or this
The case of the roman numeral is usually very important.
Depending on the notation system, the case either tells you:
a. The quality of the chord (is it G major or G minor?), or
b. The quality of the scale from which the chord is taken (does the G chord, which is acting as V, belong to the C major scale or the C minor scale?)
The former (a
) is older, and perhaps still more common. The latter (b
) is more modern, much easier to notate and read, and gaining popularity. To know which your teacher wants you to use, you'll need to consult your music theory textbook. If it's Aldwell and Schachter then it's b
.
That being said, as the dominant chord acting in a cadence, it will always have a major quality and belong to the major scale, so a V in a cadence will always be written in uppercase, under either notation system, unless it is a highly unusual piece. In Classical and Baroque it is pretty much 100% going to be uppercase.