Final answer:
Mendelssohn deviates from Classical norms largely by emphasizing emotional expressiveness and individuality in his Violin Concerto in E Minor, showcasing the shift towards the more personal and expressive musical language of the Romantic era.
Step-by-step explanation:
In his Violin Concerto in E Minor, Mendelssohn deviates from the Classical norms in several ways, one of which is by placing an increased emphasis on emotional expressiveness and individuality, which is a hallmark of Romantic music. Instead of adhering strictly to established structures like sonata-allegro form in his compositions, Mendelssohn incorporates lyrical melodies and dramatic changes in mood within movements, which differ from the structured and balanced phrases typically found in Classical compositions.
These elements showcase the Romantic era's shift towards a more personal and expressive musical language, breaking away from the more stringent, rule-based composition of the Classical era.