There are many, many hotels in Paris and prices vary a lot depending on the season, time of booking and how you book it. For this reason, we strongly advise you to use one of the known booking platforms (booking.com or Airbnb to not cite them 😉 ).
Depending on your budget, you will be able to find a room that will suit you. We would encourage the participants to take a room in walking distance of Chimie ParisTech (11, rue Pierre et Marie Curie, 75005 Paris), which is in the beautiful Latin Quarter, next to the Panthéon. This is one of the nicest and safest areas of Paris.