The major scale or the Ionian scale is one of the most commonly used scales in music. The scale consists of seven notes arranged in a particular order, that order is whole step, whole step, half step, whole step, whole step, whole step, half step, whole step, whole step, half step, whole step, whole step, whole step, half step. Each scale degree has a name. The first note in the scale is called the tonic. The second note is called the super tonic. The third note is called the mediant.
The fourth note is called the sub dominant. The fifth note is called the dominant. The sixth note is called the sub mediant. The seventh note is called the leading tone. The eighth note would be called the tonic because you've come back to the original note, you started on just up one octave You can create triads off of the notes in the major scale. To create a triad you simply play every other note for three notes in the scale.
For instance, if you were to create a triad in a C major scale starting from the tonic, you would play a C, E and G, C, E, G. If you play those three notes together, they will create a C major chord, which would be considered the one chord or the tonic. This is also called a diatonic chord because it's created from the notes in the scale. If you were to play every other note from the second note in the scale, you would play a D F and an A, which would create a D minor triad d F, A. D diatonic chord created would be the super tonic chord. I just call This the two minor chord. If you play every other note from the third degree in the scale, you would play the notes eg and B.
The D being the diatonic chord you would create would be an E minor chord, that E minor chord would be the median, or as I refer to it the three minor chord. If I were to start from the fourth note in the scale and go every other note for three notes, I would play an F A and C. This would create an F major chord. A C this diatonic chord would be called the sub dominant chord, I just call it the four chord. If I were to start from the fifth note and create a triad, the notes would be G, B, and D. This would create a G major chord. The D this chord would be the diatonic chord called the dominant, I call it the five chord. If I did this process from the sixth note in the scale, I would play the notes A, C and E. those notes will create an A minor chord.
A C, E. This diatonic chord would be the sub median, which I call the sixth chord. And last but not least, if I created a triad starting from the seventh degree of the major scale, I would play the notes B, D, and F. The D f This would create a B diminished triad. This diatonic chord is called the leading term. I call it the seven chord. These seven chords are the diatonic chords for the key of C. Why is that important? What does it even mean?
Have you ever played a song and wondered? How did they choose the chords they used? Have you ever wanted to write your own song and wondered how do I know what chords go with what chords the diatonic chords are the basic seven chords using creating chord progressions in a major key. There are lots of other chords that can and are used in creating a song in major, but you really need to have a good understanding of the diatonic chords created from major because that's what most songs in a major key are going to use. I've attached a reference chart of all the diatonic chords in all 12 major keys to this lecture. To sum up, I think it's really important to understand the pattern of half steps and whole steps needed to create a major scale and what chords can be created from those nodes.