Radium is a highly reactive element, and it reacts with many different substances. Here are some examples:

Water: Radium reacts violently with water, producing radium hydroxide (Ra(OH)₂) and hydrogen gas (H₂). This reaction releases a significant amount of heat.

Air: Radium reacts with oxygen in the air to form radium oxide (RaO). This reaction is slow at room temperature but accelerates at higher temperatures.

Acids: Radium reacts readily with acids, such as hydrochloric acid (HCl), to form radium salts and hydrogen gas.

Halogens: Radium reacts with halogens like chlorine (Cl₂) and bromine (Br₂) to form radium halides, such as radium chloride (RaCl₂) and radium bromide (RaBr₂).

Metals: Radium can react with certain metals to form intermetallic compounds. For example, it reacts with mercury to form radium amalgam.

Other elements: Radium also reacts with other elements like sulfur, phosphorus, and nitrogen to form various compounds.

Important Note: Radium is extremely radioactive and dangerous. It should only be handled by trained professionals in specialized laboratories with proper safety precautions.

It's crucial to remember that working with radium is highly hazardous and requires stringent safety measures. Always consult with qualified professionals and adhere to all safety guidelines.