During a physical change, the composition of matter remains the same. The molecules rearrange, change shape, or phase (e.g., from solid to liquid or gas), but the chemical composition, elemental makeup, and chemical bonds remain unaltered. For example, when ice melts into water or steam, the molecular structure of H2O molecules stays intact, it's just the physical state and arrangement that have changed. The atoms and their chemical combinations are preserved throughout the physical change.