Scarlatti (1655-1757) was born in Naples, during the overlap of the Baroque and Classical period. He is recognized for his many keyboard works. The majority of his keyboard works are short sonatas. He wrote 555 sonatas in total.
Scarlatti's K/ 455 (Sonata in G Major) was composed around 1755. It is simple in texture, and like most of Scarlatti's sonatas, is in binary form. The work is simple in texture, with just two voices. The music has a balance between harmonic and rhytmic drive, and it has departed the polyphonic style previous seen. The cadencial endings clear and definitive. Scarlatti's use of octave intervals and arpeggiation is also evident. The B section of the work is in the dominant key, significant because we now see modulations to relative keys in the early classical period.
At 1:38, the music goes through a harminic progression that is much more complex than previous, and the the tension of the 7th and 6th notes is much more common and present throughout.
Scarlatti's earlier sonata (K9 in D minor 'Pastoralle') is thought to be composed in 1738, and shows how Scarlatti's style changed. The work has a lots more ornamentation and the texture is a little thicker. The left hand is more in keeping with an accompanimient, while the right hand plays an ornate melody above. This is leaning back towards the Baroque period. There is less arpeggiation than in his later sonatas. Binary form still exists. Section B is in the relative major of F. The piece is sectionalized and the cadencial points are clear. The sharpened 5th is present so there is little bit of tension created but most of the tension resolves immediately.
Scarlatti's style is recoganizable in most cases, and I think its easy to identify the changes that his music went through as the periods overlapped. I think one thing that ties his music together over time is the octave interval that he likes to use often.