jesliwoo:
Hello again! Generally speaking, it is in good form to name the professors, alumni and students. It's actually kind of a balancing act.
On one hand, if you do not name them and their class year (in the case of alumni/students) it may not hold much weight. Anyone can say I spoke with professors and students. At least naming them gives the impression that the interactions you had were bona fide and meaningful.
On the other hand, do not go overboard. You do not have to list every single person with whom you have had a conversation. A handful (2-3) is more than enough to show you took the time to interact with members of the school's community. You do not get extra bonus points for reaching a target number.
Also - candidates often ask this - the admissions committees are not going to validate that you had these interactions. While we support everyone be genuine and accurate, you do not have to worry in case a professor or an alumnus does not necessarily remember you. Not every interaction is two way in its impact!