Some chemistry questions about elements, and compounds
Hello, I humbly appreciate if you will answer these ff. questions.
1. Can you tell whether a substance is an element or a compound based on its physical appearance?
2. Knowing that an element cannot be broken down into simpler substances, should it react when in contact with heat? Should it ignite? If that substance reacts, therefore it is a compound, right?
3. When a substance is heated, how do we know that it decompose into simpler substaces or did it combine with something in the air to form a new substance? Hmm, maybe this question is vague.. just a hypothesis, please.