Firstly, Haydn has written this piece using Sturm Und Drang (in English, Storm and Stress). Features of this which are evident in the piece include: Beginning in a minor key, the tense harmony in some of the minor-key writing (arising principally from diminished seventh chords and the suspensions), and the rhythmic tension of the opening, in which violins, doubled by oboes, are syncopated against an on-the-beat bass part for lower strings and bassoons. Sturm und Drang is associated with Classical music, and therefore shows that the piece was written in this time.
Also, the instrumentation shows it was written in the classical period; it is scored for two oboes, two bassoons, horns, timpani, continuo (harpsichord) and a string section containing first and second violins, violas, cellos and double basses. This instrumentation is typical of the classical period orchestra, although a few are missing, eg flute. As well as this, the horns are marked "in D" and this shows it was in the classical period as the horns did not yet have valves, so would have been played a minor 7th lower than printed.
In addition, the symphony is written in sonata form; exposition bars 1-44, development bars 45-79, and recapitulation bars 80 onwards. This structure is one of the main musical structures of the classical period. Also, the texture of the piece is mainly "melody-dominated-homophony" which is also widely used in Classical music. The texture is mainly thin because parts are doubled and in unison during the piece.
As in almost all music from the classical period, chords I and V(7) play an important role in determining the keys of the piece of music, with mainly root position and first inversion chords being used. During bars 57-64, the sequence is based on the