Final answer:
Chemists need to know about the properties of chemicals to protect themselves properly.
Step-by-step explanation:
It is important to know about the properties of the chemicals you work with because the measure you need to take to protect yourself varies from the chemical to chemical. Properties of chemicals include their physical state (solid, liquid, gas), flammability, toxicity, reactivity, and others. Different chemicals have different properties, so understanding their properties is crucial for handling them safely.