music always wants to return to the tonic of whatever key you are in. the tonic is what the key is named by. usually examples are all given in C, because the proper notes to use for C major are all white keys. (there are times when you can play some black key notes in C major, but for the sake of your ear and learning how to write music, you should forget about those until you have a better understanding of the basics)
so in C major, you have these
intervals:
C is tonic
D is a major 2nd (2 half-steps, or individual piano keys (counting black keys), or notes up from tonic)
E is a major 3rd (4 half steps)
F is a perfect 4th (5 half steps)
G is a perfect 5th (7 half steps)
A is a major 6th (9 half steps)
B is a major 7th (11 half steps)
the relationship between tonic and any interval doesn't change, so if tonic is E, then your major 2nd is F#, major 3rd is G#, etc.
Because each and every note is called a half step, the major scale can be constructed from anywhere with the following pattern, starting and ending on the tonic note:
whole, whole, half, whole, whole, whole, half
where a whole step is two half steps, or 2 individual notes.
now, the reason why this is important to know, is those intervals do NOT stand equally. each of these notes wants to go different places, with various strengths.
for example, the major 7th wants to return to the tonic harder than anything else.
these 'wants' of each individual notes is the point all music is built on. all chords, when C is your tonic, will be built from notes from the C major scale. (again, for now)
So our most basic chord progression goes through major chords built from the tonic, the 4th, and the 5th. These chords are also the only 3 chords that are major chords in a major key. (yes, you can find many songs in a major key that use major chords that are not built from the 4th or the 5th, but YOU HAVE TO LEARN WHATS RIGHT BEFORE YOU CAN DO IT WRONG. picasso could paint very realistically, blah blah blah)
So, in the key of C major, our chord built off the tonic is C major. Our chord built off the 4th is F major, and our chord built off the 5th is... G major!
How do you build a major chord? Well, heres where intervals get a little more complicated. I'll explain as we go.
To make a major chord, you take the 1st, the major 3rd, and the perfect 5th of the root note. (ROOT is not the same thing as TONIC. tonic is the center of your key, and the root is the note most suggested by the chord. as in, the note you would naturally gravitate to singing over a chord.)
So for C major, this is fairly simple because the root and the tonic are the same note.
C-root
E-major 3rd
G-5th
BAM! tonic chord, done! in C major, this is always the chord the song wants to end on. (songs that feel unfinished at the end of them don't end on tonic)
Our chord built from the 4th is F major, and it will also use the major 3rd and the perfect 5th, but instead of the KEY's (C's) major 3rd and perfect 5th, it will stem from the note F. So here's our F chord.
F-root
A-major 3rd of F (4 half steps up from F)
C-perfect 5th of F (7 half steps up from F)
but note that while we are constructing it based on intervals around the note F, those notes (A and C) both show up in C major, as the major 6th and tonic, respectfully. this is why F major fits in the key of C major.
Our chord built from the 5th is G major:
G-root
B-major 3rd of G (major 7th to our tonic of C)
D-perfect 5th of G (major 2nd to tonic)
Now, the 5th chord has a very powerful want to go back to the tonic chord. ALL of these notes want to go back to C a decent amount, especially that B.
Basically, music is all built on intervals and what they want to do in relationship to the key you're in. I'm tired of typing but maybe I'll do some more later. 'Music theory' while it is complicated, makes more and more sense the more you learn.
Okay, actually, one more thing-- I just realized I was doing this and I hate when people do it, so I'm gonna explain why these naming conventions make sense. until you understand the basics from earlier, and understand those basics in any key, don't worry about applying any of this info. I am only mentioning it because I know of common questions people have. Like:
"Why 'major' 3rd? 'perfect' 5th?"
Interval relationships NEVER change. However, in a minor key or minor chord, there is still a 3rd. But its a minor third.
Here's every interval.
TONIC-starting note
MINOR 2ND-1 note up
MAJOR 2ND-2 notes up
MINOR 3rd-3 notes up
MAJOR 3rd-4 notes up
PERFECT 4th-5 notes up
TRITONE-6 notes up
PERFECT 5th-7 notes up
MINOR 6th-8 notes up
MAJOR 6th-9 notes up
MINOR 7th-10 notes up
MAJOR 7th-11 notes up
OCTAVE-starting note, but an octave higher
So intervals classified as major are classified that way because if they are flatted (dropped a half step/note) they will become minor. THIS IS NOT HOW YOU CONSTRUCT A MINOR KEY, but it is important to know anyway.
The perfect 4th and perfect 5th are called such because they show up in any non-exotic key. There are not major and minor versions of them. They just are.
The tritone is a very unique interval. It is the least consonant, meaning it sounds the worst, or most dissonant of the bunch. You will never see it referred to as the tritone in a musical context, usually it will be called a DIMINISHED FIFTH. but there are times, though rare, where it functions as an AUGMENTED 4th.
Diminished-flatted by a half step
Augmented-sharpened by a half step
OK nope I'm done. More later maybe. Check out
www.musictheory.net and google any questions. some people make minor mistakes, but in my experience the easiest way to learn theory is to LEARN IT FROM EVERYWHERE. because often something that doesn't make sense to you will make sense when its explained in a slightly different way.
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