The movement is in sonata-allegro form, and characterized generally by the regular phrasing of its cut-time meter (in 2- and 4-bar groups). The exposition, development, and recapitulation sections are roughly balanced on a ratio of 4-3-5, and the textural qualities of the three sections are basically homophonic-contrapuntal-homophonic (with considerable quasi-contrapuntal decoration of the harmony). Orchestrally, the strings provide the foundation for most of the writing, although the winds are particularly important for their use in the major transitional points of the form. The beginning of the development section (ms. 102-105) and the retransition (ms. 160-166) are the primary examples. Special mention may be made of the bassoon writing in this movement, which is unusually active. The exploitation of the octave sonority, which is characteristic of Mozart's style in general, finds expression here in the three-octave doublings of the melodic line often encountered in the movement (ms. 14-15, 70-71, 89, and similar passages throughout).
Also typical of Mozart's style is the extensive chromatic embellishment of melodic lines found here and throughout the work as a whole (see 2nd subjects in 1st and 4th movements, accompaniment figure to 1st theme in 2nd movement, among others). Rhythmically, this movement is rather square, although good use is made of syncopation and agogic accent near the beginning of the development section (ms. 114-124). Generally, however, the distinctive rhythm of the opening motive dominates the entire movement. The composer's characteristic harmonic daring may be seen in such passages as the beginning of the development section (leading from g-minor to f-sharp-minor, ms. 101-105), and the decorated pedal dominant n the retransition (ms. 160-166).
The distinctive opening theme is announced by the strings, doubled at the octave in the violins over a homophonic accompaniment in the low strings. It...