As of upir first novel isn't already hard enough, the process gets even more complicated when you consider what goes in to just one chapter. There is no one totally "right" answer to this question, many authors have their own preferences. Some like 'em short and to the point, others really do enjoy bigger chunks. It's all in how you think of your story.
Nothing in any fiction you write will be more important than Chapter One. It is the beginning of all things in your imagined universe. Om the reader's mind, it's the first thing they "see" when they open a book and turn the pages. Prologues are a completely separate matter, so let's just skip them here. All I want to examine for the moment is just Chapter One.
It's not unreasonable for you to think of your book as a movie on paper. It's not an actual screenplay, though it could be--someday (if you're lucky). To make something/anything "happen" in your story, you've got to write it down or type it. Readers don't know what you have already figured out, nothing in your imagination exists until you put it on paper. That's how they see it when they read your stuff.
Some of the very best movies have memorable opening scenes. Even if you can't remember anything else about that film you saw years ago, chances are good that the opening scene(s) stuck with you. Chapter One sets the stage for everything else that happens later. Characters are introduced much like you see them in a movie, walk on and say something that tells you who they are and why they matter in the scheme of things.
My own rule of thumb is to tell you (as the reader) everything you need to know about the story within three to five chapters. By the end of chapter three, four, or five, you'll know just enough to make a decision. Continue reading, or not?
My first novel begins with a funeral, everyone you see and hear from says something important. What looks like a solemn or sad moment is actually more--because of what you learned from those mourners. From that point on, we're off to the races with the turning of each page. Calm and collected gives way to uncertainty, fear, and lots of stress. By the end of chapter three, you have that choice to make. Do you want to know more, or...
There is a reason "why" anyone does anything. Who and what they are plays a big role in what they choose to do. Good Guys fight the Bad Guys, because they don't want them to win. Sometimes, heroes and heroines get pulled in to something they don't immediately understand. Even so, they must still choose to get involved or walk away. Why is it their problem now, when it wasn't just a few sentences ago? Answer that, and you've got yourself a fast start.
All novels have a beginning, a middle, and an end. It's not mandatory for every chapter to contain plot twists, they just need to be important or relevant to the story. Why does anyone have a quick sidebar conversation with somebody who is quite busy just now? Because they have something important to say, or a real need to know why something-anything "is." Using a tense moment like that to fill in vital gaps does a lot to add momentum to any story.
Chapter give your story to the reader in bite-sized amounts. That's what they're supposed to do. When you write big-big chapters, it's like asking anyone to eat a massive sandwich over and over again--they can, but it will be difficult. Instead of having a full stomach that forces them to stop, many readers can't remember all of what happened in the last chapter. So, they don't.
I wasn't entirely joking about books that are made in to screenplays. People who write movie scripts are asked/tasked with putting enough bits and pieces of your story in to a movie format, so that anyone who watches it will get the major points you were trying to communicate. Big novels are summarized, best moments are cherry-picked for the actors. Gun battles and car chases can always be made as long or short as needed. You'll make it easier for Hollywood to like what you did, if those chapters in your book are just the right size to be devoured easily.
That's why the anatomy of chapters should matter.