Here's why:
* Chemical Formula: A chemical formula uses symbols and numbers to represent the types and number of atoms present in a substance. For example, the formula for water is H₂O, indicating two hydrogen atoms and one oxygen atom.
* Pure Substance: A pure substance is composed of only one type of molecule or atom. This means all the particles in the substance are identical.
Examples of pure substances:
* Elements: These are the simplest pure substances, made up of only one type of atom. Examples include gold (Au), carbon (C), and oxygen (O).
* Compounds: These are formed when two or more elements combine chemically. Examples include water (H₂O), carbon dioxide (CO₂), and table salt (NaCl).
Things that are NOT pure substances:
* Mixtures: These are combinations of two or more substances that are not chemically bonded. Examples include saltwater (salt and water), air (nitrogen, oxygen, and other gases), and a salad (vegetables, dressing).
Let me know if you'd like more examples or have any further questions!
