Here's what you need to know:
* Pure compound: A substance made up of two or more different elements chemically combined in a fixed ratio.
* Chemical formula: A symbolic representation of a compound using element symbols and subscripts to indicate the number of atoms of each element.
Examples of Chemical Formulas:
* Water (H₂O): Two hydrogen atoms (H) and one oxygen atom (O) are combined.
* Carbon dioxide (CO₂): One carbon atom (C) and two oxygen atoms (O) are combined.
* Sodium chloride (NaCl): One sodium atom (Na) and one chlorine atom (Cl) are combined.
Key Points:
* The subscripts in a chemical formula indicate the number of atoms of each element. If no subscript is written, it is assumed to be 1.
* The chemical formula gives the exact ratio of elements in a compound, which is always fixed.
In summary, there is no single formula for all pure compounds, but we use specific chemical formulas to represent each compound's unique composition.
