1. State of Matter: Chlorine is a gas at room temperature and pressure.

2. Color: Chlorine gas is yellowish-green.

3. Odor: It has a pungent, suffocating odor, similar to bleach.

4. Density: Chlorine is denser than air. This is why it tends to collect in low-lying areas.

5. Boiling Point: Chlorine has a boiling point of -34.04 °C (-29.27 °F). This means it can be liquefied under pressure.