A simple solution is to break up the group; give the students the option to find another seat farther away from their peers, or assign them one if the problem persists. Often times, groups like this will have a "ringleader" that the teacher could isolate. The remaining students will likely pay attention without the presence of the ringleader student.

I would suggest that whatever form of seating chart you have to switch it up. It kind of sounds like you have clusters. I would suggest you do the U-shape desks or the transitional desks. Then you can break up students who talk more with the students who do not talk. Same can go for group assignments.

I would inform the group of students if the talking continues you will have to separate them and/or create assigned seats for them. This allows the student to have control over their decision. Giving students a choice to self-manage their own behavior can result in a better outcome than stopping the behavior all together. Students should also be reminded of appropriate times for classroom collaboration and when talking should occur like the lunchroom, recess, group projects, etc. If a lot of students in your class like to talk, I would suggest offering topics of choice to students for a whole class discussion. Restricting students from talking usually results in them wanting to talk more so finding positive alternatives for them to collaborate and connect to your curriculum would be more helpful for everyone. If off-topic conversations occur provide students with verbal reminders and be consistent with consequences if the discussion continues. Make sure classroom rules are clear and practical for all students. Remind students they are accountable for their actions and decisions and consequences will be given to those who choose not to follow the rules. Students should be informed of what those specified consequences are. This helps set the tone that if the students choose to not follow the rules, then they are choosing to get their student choice revoked.

I think the best way to handle this is to separate the students. Maybe if they are around new people it will help with their attentiveness.

When a group of students talk too much during class and disturb the learning environment, it can be frustrating. Establishing clear and constant expectations for respectful behavior and active listening in the classroom is one useful approach.