There are 12 notes on a music scale. They are the based 7 note scale - A, B, C, D, E, F, G, and their transition notes add up to 12.
Sharps and Flats
1. A
2. A# (or Bb)
3. B
4. C
5. C# (or Db)
6. D
7. D# (or Eb)
8. E
9. F
10. F# (or Gb)
11. G
12 G# (or Ab)
Chord
A chord is made up of 3 notes, called a triad.