Tense, bluesy, and commanding. Wants to resolve to the tonic.
The C Dominant 7th chord (C7) is built on the root note C with component pitches C, E, G, A#. Formula: [0 - 4 - 7 - 10 semitones]. Category: Dominant 7th (4 tones). Primary genres: Blues, Jazz, Rock and Roll, Funk.
Notes in this chord: C - E - G - A#
Use as the V chord to create a strong pull back to your I chord.