* Capital letters: These represent the symbol of an element, which is a unique one or two-letter abbreviation assigned to each element. For example:
* H stands for Hydrogen
* O stands for Oxygen
* Na stands for Sodium
* Fe stands for Iron
* Lowercase letters: These are used only if there are two or more of the same element in the formula. They specify how many atoms of that element are present in the molecule.
* H₂O means there are two hydrogen atoms (H) and one oxygen atom (O) in a water molecule.
* CO₂ means there is one carbon atom (C) and two oxygen atoms (O) in a carbon dioxide molecule.
In summary:
* Capital letters represent the type of element.
* Lowercase letters represent the number of atoms of that element.
Let me know if you'd like any further clarification or examples!
