By applying the formulas for seventh chords to the C major scale, the following series of chords is created. These are called scale tone seventh chords. If you analyze the notes of these scale tone 7th chords, you will notice that they are all based on the C major scale tone triads and each one has another 3rd interval added above it.
Here are the scale tone 7th chord arpeggios in the key of C major. Learn them from memory and then transpose them to all the other keys. It is a good idea to write down the notes of each chord in each key, as this tends to reinforce the knowledge in your mind. If you have trouble doing this, consult the chart on the following page.