A dominant seventh chord
A7 chord for piano with keyboard diagram.
Explanation: The A dominant seventh is a four note chord. You can see the four notes of the A seventh chord marked in red color. The chord is often abbreviated as A7.
Theory: The A seventh chord is constructed with a root, a major third, a perfect fifth and a minor seventh.
Fingerings: little finger, middle finger, index finger, thumb (left hand); thumb, index finger, middle finger, little finger (right hand).
Notes: A - C# - E - G
A7 - inversions
Explanation: The images below show the three inversions of the A dominant seventh chord. A7/C# is a A dominant seventh with C# as the bass note, A7/E is a A dominant seventh with E as the bass note and A7/G is a A dominant seventh with G as the bass note. Note that the fifth sometimes are omitted.