Ionian, the king of all modes…
This is the most important mode in music, also known as major. To be in Ionian a piece needs to be confined to only the notes in a major scale, any of the 12 major scales – no exceptions. Any Ionian tune can be written, played or sung in C major, and there will be no added sharps or flats. It’s that simple.
Countless very simple tunes are in Ionian mode. Some have been composed recently, others have been around for centuries. Here is what Mozart did with Twinkle Twinkle Little Star, though he did cheat now and then, writing it in the key of C but slipping in a few black notes here and there:
Cousin to the regular 7 chord
To illustrate these chords I wrote a little tune for the LH to practice them in root position along with a simple melody.
Here are ways you will see these chords notated as symbols:
- X maj7
- X M7
- X MA7
- X Ma7
- X maj
X maj7 is most common most clear.
Take a regular 7 chord, then change (b)7 to maj7. There is close to zero problem with spelling, because it is beyond rare to see it written more than one way in notation. Before around the end of the 19th century, it was extremely rare to end a piece of music with Xmaj7. Starting with Debussy and his contemporaries, this change, and it is extremely common today in jazz and pop.