How Long Is a Chapter?
A chapter is as long as the writer needs it to be to fulfill his purpose. Some are short, and some must be longer because of what it commits to accomplish. Having worked at constructing chapters for several unfinished books, I've come up with a sort of recipe. Another writer would add other additional ingredients, but this reading will give beginning writers a guideline to follow. Adjust these checkpoints to your needs.
One chapter in a novel should be equal to one scene in a screenplay. Think about your experience with high school drama, and setting scenery. Once the stage is set, you can make changes and adjustments, and certainly additions of description. If your characters congregate at the mall for lunch, keep all the action that happens in the mall in that chapter. In your writer's head, envision your scene in detail, possibly more detail than you share with your reader. Paint the image of your scene using all the senses--what can your reader see, feel, hear, smell, or taste? The more specific your description the better your reader will be able to envision the same scene you paint.
A good chapter has a beginning, middle, and an end, though it need not be presented in chronological order. The beginning introduces the people, places, and things that will happen in the story. The beginning or the middle section are both good for slipping in elements of foreshadowing. Depending on your writing style, foreshadowing may be an element that is edited in, after its consequence appears later in the story.
By the middle section of your chapter, your reader is aware of a conflict; it could be a conflict between characters, between the character and nature, between the character and his conscience, or a conflict caused by a mental or physical disability.
Remember to approach your manuscript with a "show, don't tell" attitude. Telling your reader too often insults his intelligence. Plant dialog and actions that leave your reader to insinuate, by leaving a sly hint or suggestion.. Be indirect in an artful sort of way. Plan what questions you want to leave your reader asking.
A chapter in a novel needs to move the story along. Some writers are able to sketch out an entire work with bare bones details. They know how the story will end before they begin the formal writing process. Other writers are more comfortable letting the story evolve during the writing process. Either way is fine if it works for you, and I myself have used both methods at different times.
The ending section of your chapter must take care of some serious literary business. Do you remember the term "denouement" from your literature classes? This is where the conflict mounts to a crescendo, the tension is as tight as you can make it, and then your situation is resolved. The building of tension should be in the beginning, the middle, and the end. After the resolution, let your reader breathe again and wrap your conflict up.
A good writer always proofreads and edits. Edit your chapter when you finish it, or better yet, lay the manuscript aside for a couple of days, or a week, and then edit. If you have trouble proofreading your own work, I have a hint from a very old lady who had been a proofreader for her printer husband. Read your pages, word-by-word backwards. In that way you can catch accidental misspellings. This is tedious work, which may be required when sending a manuscript to a publishing company.
Remember aspects like tone and mood. Don't be shy about using a thesaurus, like the one at http://www.visualthesaurus.com . Use a site like http://www.dictionary.com to double check that you are using the correct meaning or spelling of a word. I like to enter my proposed noun or verb, hit enter, and confirm that definition one, two, or three is exactly what I meant.
Remember to use symbolism. Remember the importance of vivid imagery. Let your creative muse loose. Write more than you need to if you get "on a roll" where the words are coming to the page easily. You can always edit out later. It is more difficult to edit it later on, as you need to match the mood and tone that already exists. If there is some word that you want to use, but you can't think of it, go ahead and write in a blank line, and continue with your thought. If you begin to experience writer's block, take a break. When you come back to your writing, you may find a problem that was blocking the flow of your story. Analyze your work, and don't be unwilling to change large sections of your manuscript if you discover you've written yourself into a dead end.
A chapter is not a certain number of words. A chapter has a beginning, middle, and an end, and moves the action of the story from one scene into its next scene, or location. A good chapter could stand alone as a short story. A good writer edits, and edits, and edits. Like your mind, your story is always open for further fine-tuning.