Interactive textbook ch. 14 chemical reactions | PDF - Free Printable

- A chemical formula is a symbolic representation of the composition of a substance, showing the types and numbers of atoms in a molecule or compound.
- Chemical formulas are written using element symbols from the periodic table. Subscripts indicate the number of atoms of each element present. If no subscript is shown, it means there is only one atom of that element.
- To balance a chemical equation, adjust coefficients (numbers placed before formulas) so that the number of atoms of each element is equal on both sides of the equation. Never change subscripts when balancing, as that alters the identity of the substance.
- A chemical equation represents a chemical reaction, showing reactants on the left and products on the right, separated by an arrow. It must obey the Law of Conservation of Mass — atoms are neither created nor destroyed.
- Example: In H₂O, the “2” subscript means two hydrogen atoms; oxygen has no subscript, meaning one oxygen atom. The formula indicates one molecule of water contains two H atoms and one O atom.