The Ionian Mode is the term given to the major scale. To reiterate the interval pattern it is: 2212221
For the key of C we have: C D EF G A BC. Notice that I put no space between E and F or B and C. This is in keeping with the interval pattern. There is no sharp or flat between B and C nor E and F. This as you are about to discover is the basis for the modes.
What if we started our scale on the 2nd degree? Remember degrees? Each note is given a number. So if we started on D and play an octave to D we would have D EF G A BC D. Written out as degress we would see that the interval pattern has shifted from 2212221 to 2122212. Notice that the half steps are one place earlier in the scale. If we play from C to C we are playing a major scale. If we play the same notes from D to D we are still playing the same notes and it will still sound major until we add a chord behind it. To address this next portion it is necessary that I explain about chords.
Technically it takes 3 notes to make a chord. To make a major chord you use the 1st, 3rd and 5th notes of the major scale. For a C major you would use the C, skip the D and use the E. Skip the F and use the G. This gives you C, E and G making a major chord. To make the rest of the chords we simply start on the next scale degree and use the same methodology. Use every other note to form the triad. So if we start on the D skip the E we would use the F. Skip the G and use the A. So we have the notes D, F and A. This is where the magic happens. Notice in Cmaj there are 4 half steps to the second note E of the chord and only 3 half-steps to the 3rd note G. But if you look at the same process for the D or 2nd degree, can you see that there are only 3 half steps to the note F and there are 4 half-steps to the note A. This is just the opposite. The interval distance from the D and A are the same as the interval distance from C to G. It is that middle note that changes.
In practical application we refer to this as a flatted 3rd. A major chord uses a 1, 3 and 5 from the scale. When you start on D that first half step comes earlier in the scale and the results is the middle note of the chord is a half-step down or flatted. This is what constitutes a minor chord. So to put it together, if you play the Cmaj scale, but play from D to D, you are still playing a Cmaj scale, but if play from D to D and use the chord formed from the second degree which is Dmin you are now playing in D minor. This is the second mode and it is called Dorian. I have created a video that demonstrates this. In the demo, I used most of the modes. In the demo I play the scale from C to C and then use a note pattern over Cmaj. Then I play the Cmaj scaled from D to D follow by she same exact note sequence each time through but I changed the chord behind it. Listening you should be able to hear the different flavors or colors of the music. We refer to those flavors or colors as modes. The minor pentatonic is simply a minor mode with 2 of the notes removed. This gives you an idea of where we’re headed.
In the next section we will cover the concept of the shifting half steps more and go through the modes.