Sorry for a beginner question
I thought all the white keys are all major notes. On a C major scale this is the case, so why on a D major scale, the key F becomes F# and key C becomes C#?
D major has 2 sharp notes in it. This is due to the intervals between the notes of a major scale: W-W-H-W-W-W-H. This translates to a whole step (W) being a jump of 2 keys (1 black and 1 white), and half step (H) jumping from one key to another (black -> white / white -> black, or white -> white for E-F and B-C). However, there are 12 chromatic notes within an octave, so E-F and B-C are half steps.
So, when you apply the interval pattern for a major scale on D, you'll find that the 2nd scale note, E to F, is only a half step. So, you go up another half step to satisfy the 2nd whole step, yielding E-F#. The same applies to B-C#.
The fact that C major is all on white keys doesn't matter. What matters is the step interval between the notes of a scale, or number of white and black keys between the notes. Yes, you can have a scale that has all sharps (B# major is just C major, but written differently).
bigyihsuan has already provided a great response, but I thought I'd chime in too.
By the sounds of your question, you haven't learnt what intervals are yet -- that's cool! Not long ago, the reason why chords had certain notes totally baffled me, so you're in good company!
You should know that, in music, you're dealing with 12 notes:1) C - 2) C#Db - 3) D - 4) D#/Eb - 5) E - 6) F - 7) F#/Gb - 8) G - 9) G#/Ab -10) A - 11) A#/Bb - 12) B, and that's it!
** Wherever I used a slash (E.G. F#/Gb), I was talking about notes that are enharmonc. That means they sound the same when you hear them, but they're spelt differently depending on the scale you're using.
This comes back to your question: to make a major scale, we use this formula: W-W-H-W-W-W-H. "W" means "whole step" and H means "half step". What does this mean? Go back to the 12 notes I wrote out. When you move by a whole step you skip one note, and when you move by a half step you move straight to the next note. So, in the case of C Major, we start on C and then move a whole step to D. and then a whole step to E, and then a half step to F.
The full formula makes: C - D - E - F - G - A - B - C.
So what about D Major?
D => WHOLE STEP => E => WHOLE STEP => F# => HALF STEP => G => WHOLE STEP => A => WHOLE STEP => B => WHOLE STEP => C# => HALF STEP => (Back to) D.
In Hooktheory, when you want to choose a key for your song, a big circle full of notes pops up. This is called the circle of fifths. Every time you move right, the Major Scale of that key gains one sharp note. So C Major has no sharps (all white keys), but G Major has one (F#) and D Major has two (F# and C#', and so on). But what happens if you go left of C? That adds flats! So F Major has one flat (Bb) and Bb Major has two flats (Bb and Eb). This seems really confusing until you remember that Bb and and A# are enharmonic. That means that the only difference between F Major and C Major is Bb/A#.
That's because when we write a Major scale (W - W - H - W - W - W - H), we need to have a different letter in each place so we can tell them apart. If you've read about advanced theory with double flats (Abb = G) and the like, don't worry about that just yet. Master the basics first, and then that stuff will seem easy later. Just remember: a sharp note goes up a HALF STEP and a flat note goes down a HALF STEP.
So when we write the F Major scale, we write:
F - Whole Step - G - Whole Step - A - Half Step* - A#/Bb - **Whole Step - C - Whole Step - D - Whole Step - E - HalfStep - F.
==> But we don't write "A#" because we need a different letter in each place, so we write "Bb".
A great way to work on this is to learn the "musical alphabet" (A- A# - B - C - C# - D - D# - E - F - F# - G - G# - A - A# - B) and practice writing out the major scales of each letter using the formula,W-W-H-W-W-W-H Just remember which notes are enharmonic, and remember that you need a new letter in each spot.
If you play piano, every time you move up one key (black or white), you move up a half step; guitar is a bit different, but when you move up one fret on the same string, you're moving up a half step,
I'd really recommend the Hooktheory book if you haven't bought it already. It explains all of the above much more precisely and shows you how to use it to create your own music.
Hope I helped!
Ah thanks a lot guys, I think the formula helps me to understand now. However, I've been reading the first chapter of the first book, and nowhere is this mentioned. Is it at a later stage?