My co-worker talks too much and I want to tell them to be quiet.
Why do you want your co-worker to be quiet?
My co-worker's noise is distracting me in my working environment.
If someone is making a disturbance at work that is affecting your ability to complete your duties, it is okay for you to tell that person to be quieter. People at work should be professional and try to maintain office decorum at all times. If your co-worker is being noisy, they are breaking that etiquette and should be gently told to be quieter so that others can perform their work without distraction.
The world would be a calmer place without people that distract me at work.
I understand your need to focus at work. It's important to respectfully make this request when it is needed.