Susana heats up a sample of red crystals. While the sample is being heated, a gas is released and a blue powder is left after the heating. Is the sample of red crystals an element or a compound? Explain your answer.

Answer:

The red crystal sample is a compound. This is because it was broken down into two different substances—a gas and a blue powder—when heated. Elements are pure substances that cannot be broken down into simpler substances by chemical means or heating.