C7 Chord

Start with C major: C, E, G. Add B flat, a minor seventh above the root. The complete spelling is C-E-G-B flat. Counting upward from the root gives 1-3-5-flat 7. The flat in the formula describes a seventh lowered from the major scale; it does not mean that the written note must always have a flat sign.

B flat is the only black key in this four-note shape. Change it to B natural and the sound becomes Cmaj7.

Play the four notes together, then move only the lowest note up an octave each time:

Each version still contains the same four pitch classes. The bass position changes, so the chord may feel lighter or heavier even though its name stays C7. A slash symbol specifies the actual bass note in an arrangement; Chord Inversions explains the distinction.

In F major, C7 is the V7 chord. Its third, E, can rise a half step to F; its seventh, B flat, can fall a half step to A. Try playing just those two notes, then the two destination notes, before adding the other chord tones. You can hear the small voice movements more clearly than when you move two full chords at once.

That is a common resolution, not a rule for every use of C7. A dominant-seventh chord may also appear in blues or lead temporarily to another chord. Dominant Seventh Chord explains why the chord name and its harmonic job are related but not identical.

Keep C, E, G and raise only B flat by one semitone to hear Cmaj7. The triad remains major, but the top interval changes. Alternate the two at the same volume, then return to C7 and resolve it to F major. That three-part comparison makes the extra pull of the minor seventh easier to recognize than a sound adjective alone. See Cmaj7 Chord for the other spelling and its own inversions.

Find the root, build a major triad, and add a note a whole step below the next octave of the root. Play C7, sing its seventh, and move that sung note down to A. Then play the full F major chord. Repeat from the first inversion until you can still hear the resolution with a different note at the bottom.