Here's a breakdown:
* Elements: Pure substances that cannot be broken down into simpler substances (like oxygen, hydrogen, carbon).
* Chemically bonded: The elements are held together by forces of attraction called chemical bonds.
* Fixed ratio: The elements are always present in the same proportion within a specific compound.
Example:
* Water (H₂O): It's a compound made up of two hydrogen atoms (H) and one oxygen atom (O) bonded together in a fixed ratio of 2:1. You can't change this ratio and still call it water.
Key points to remember:
* Compounds have different properties from the elements they are made of. For example, water (H₂O) is a liquid, while hydrogen (H₂) and oxygen (O₂) are gases.
* Compounds can be broken down into their constituent elements through chemical reactions.
* There are millions of known compounds, and new ones are being discovered all the time.
Other examples of compounds:
* Salt (NaCl): Sodium (Na) and chlorine (Cl)
* Sugar (C₁₂H₂₂O₁₁): Carbon (C), hydrogen (H), and oxygen (O)
* Carbon dioxide (CO₂): Carbon (C) and oxygen (O)
