Scales are typically learned in one octave ...meaning the scale pattern of notes is within the 12 chromatic notes.

          The chromatic scale notes are: 

                    C  C#  D  D# ...

This question can be both simple and complex... depending on what points we're trying to understand about modes.

First, we need to know that modes are simply scales.  Every mode is a scale, and every scale is a mode.

For example, we have 7 notes in the key of C major:  C D E F...

There are 7 modes of the major (diatonic scale).  These modes are variations of the diatonic major scale ("Ionian").

Here are the 7 'diatonic' modes with a brief description of each modes unique quality / sound:

1. Ionian  --->  "the major scale"

2. Dorian  --->  "a...