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