Scales:

Scales make use of pitches and intervals to provide a pallet of notes from which we can create melodies and harmonies (a melody is something you can whistle, a harmony is the accompaniment).
Remember the term Diatonic? It’s back and you won’t want to forget it again.

It’s latin and basically means 7 of tonic. What’s tonic? Tonic is the name we give to the pitch that is the heart of each scale, home-base if you will. Any pitch can be tonic, but only 1 pitch in a given scale can be tonic at a time. Diatonic scales are split into 2

categories, Major and Minor. Which name depends on what intervals are in the scale (see the relationship here?)
Here is a Major scale where C is tonic. Each pitch has it’s interval (relationship) to tonic below.

CDEFGAB 1 M2 M3 P4 P5 M6 M7

Here is a minor scale where C is tonic with corresponding intervals below. C D Eb F G Ab Bb

1 M2 m3 P4 P5 m6 m7

The minor scale also has 2 close relatives, harmonic minor and melodic minor.

Harmonic minor

C D Eb F G Ab B 1 M2 m3 P4 P5 m6 M7

Melodic Minor

C D Eb F G A B 1 M2 m3 P4 P5 M6 M7

Modes:

Modes are a way of looking at scales from different perspectives, or more accurately, different tonics.

Remember C Major?

CDEFGAB
1 M2 M3 P4 P5 M6 M7

In this scale, C is tonic and is the leader of the group. C is a natural leader and when you play this scale, it sounds right. What if we take C’s group and let G be the leader? (Forgive me as we talk about notes like they’re people)

GABCDEF 1 M2 M3 P4 P5 M6 m7

G has the same relationship with almost all the other notes as C did, except for 7. C had a Major relationship with 7, while G has a minor relationship. When you play this scale, G makes an OK leader, not as strong as C but does pretty well and you can get used to it.

Lets see what happens when we leave D in charge

DEFGABC
1 M2 m3 P4 P5 M6 m7

D has a minor relationship with 3 and 7, compared to C who has a Major relationship with them. D’s relationships have more in common with G’s than C’s. D sounds a lot like a minor scale, it’s relationships are close, but it has a Major relationship with 6.

Let’s look at one more

BCDEFGA 1 m2 m3 P4 d5 m6 m7

B has much different relationships with this group of notes than C did. When you play this you’ll find that B isn’t very good at being in charge, it’s hard to hear B as a leader and takes some real getting used to.

We can repeat this process for each note of any scale to derive it’s various Modes, each of which have a unique sound character.