Physics as an independent academic discipline is the study of space, matter and energy for the purpose of discerning general laws or general principles. Physicists attempt to study complexity and reduce it to simplicity. As an example, James Clerk Maxwell studied electromagnetism. He reduced all electromagnetic theory into four mathematical equations. These are now named "Maxwell's Equations." Sir Isaac Newton is credited as the father of the science, because he was the first person to attempt to describe natural forces in the language of mathematics.
Chemistry begins with some of the axioms of physics, specifically the structure and the behavior of atoms. Chemistry, however, is more interested in how atoms behave with one another as they form molecules. So instead of reducing to the simplest principles, chemists want to know how elements interact with one another when they are combined into compounds. Chemists still seek principles, but they seek principles that can describe these intermolecular relations. Chemistry overlaps with biology in the study of "molecular biology."
The different emphases of physics and chemistry give each of the disciplines a different character. There is a degree of friendly rivalry between physicist and chemists, and physicists have sometimes said that chemistry is "physics with less rigor." Nobel Prize winner William Lipscomb replied to this claim by pointing out that chemistry contains first principles that are too complex for physicists. He is hinting at complexity theory, which says that complex systems are emergent and therefore more unpredictable. Chemists experiment put putting things together to see how they behave, while physicists try to take things apart.
If this is the case, then there are special challenges to scientists who are focusing on the interdisciplinary fields of physical chemistry or chemical physics. They study chemical compounds at the atomic and subatomic level to determine how time, force, motion and thermodynamics affect the intermolecular phenomena of reactions, tensile strengths, surface tensions and ion transfer. Students pursuing this major have to become proficient in both disciplines prior to studying the interdiscipline.