The story takes place on Camas Province, where Xander and three other medics are going to name and register a baby into the Society system. The story also goes to Central which is another city in the Society (where Cassia lives). Later in that chapter, Cassia goes to a sorting center, where she goes on the computer to sort matches.
The time period of this book seems like it is in the future because of what machines and devices they have. I imagine the Society to be a clean place with houses that all look the same. There is no time year or season in the book.
The geography and environment isn't described in the book. I image the Society as a happy and sunny place. The community has clean air and is clean.
In Central, it seems crowded because it says that Cassia passes people when she goes to the sorting center. Since Central is also the capital city of the Society, I assume there are a lot of people.
In the book, it talks about air trains, tablets, and ports. The air trains are their kind of transportation, like a bus. The tablets seem like advanced medicine: the green is to calm you, the blue one is supposed to be able to keep you alive for a little while if you have water, and the red one if to make you forget everything that happened in the past 12 hours. The ports are like monitors that hold all of your information: your name, birthday, matches, etc. (you can also get information and call people on it too)
The overall mood and atmosphere of the book is happy, dreamy, relaxed, and peaceful. The Rising is just starting to take over the Society, and since no one knows it yet, it it like a normal day. In the Society, people are peaceful and go about their daily lives.
The setting affects the story because it describes what is going on. The Rising is taking over the Society, where Ky, Cassia, and Xander live and work. The setting is contributing to what is happening in the story because Cassia goes to the lake to meet Ky.