Naming chapters, rather than numbering them, is a personal choice for the writer. Some writers give their chapters deeply symbolic or metaphorical names, while others choose literal chapter names. There is usually no deeper reason for chapters to be named, numbered, or both; it is simply a stylistic and personal choice. Regardless, some things can be said about the numbered chapters in 1984: for example, the simple numbers might be representative of the emotionless and disaffected state of humanity. To apply names to the chapters, each chapter must be analyzed for its overall themes, topics, and deeper meaning.
For example, the theme for Chapter 1 might be simplified to "Rebelling Against the Collective."
...Winston's hatred was not turned against Goldstein at all, but, on the contrary, against Big Brother, the Party, and the Thought Police; and at such moments his heart went out to the lonely, derided heretic on the screen, sole guardian of truth and sanity in a world of lies.
(Orwell, 1984, msxnet.org)
This chapter explains some of the world in which Winston lives and shows that part of his mind is moving towards individualism; he cannot sustain the herd-hatred of Goldstein during the collective Two Minutes of Hate, but instead finds his hatred moving with his subconscious feelings.
In stark contrast, the theme for the last chapter might be "Resignation to the Collective," as Winston finds himself truly believing in the Party and in Big Brother, even as his experiences have proven the Party to be corrupt, oppressive, and evil. Because he could not keep his individuality in the face of brainwashing, he has failed to become an individual and is instead a pawn, like all the other citizens.
To sum up, examine each chapter and simplify their themes into a short statement; these can act as chapter names.