This means that each side of the equation must represent the same quantity of each element in other words have the same number of each kind of atom. Reactants react and produce products! įor Example: In this reaction, sodium ( Na ) and oxygen ( O 2 ) react to make a single molecule, Na 2 O Na + O 2 -> Na 2 Oīalancing Equations The Law of Conservation of Mass states that in a chemical reaction, the quantity or amount of each element does not change. The right side indicates the combination of compounds and molecules after the reaction, and they are called the products. The combination of compounds and molecules before the reaction are on the left side of the arrow, and they are called the reactants.
Reading Chemical Equations The two sides of the equation are separated by an arrow. CH 4 + 2 O 2 -> CO 2 + 2 H 2 O Coefficient The combination is written as a set of chemical formulas, separated by + symbols. Reading Chemical Equations Each side of an equation represents a combination of chemicals. For example: 2H 2 SO 4 – 2 molecules of Sulfuric Acid Ĭoefficients 2H 2 SO 4 – 2 molecules of Sulfuric Acid A coefficient is distributed to ALL elements in a compound 2 – H 2 (for a total of 4 H atoms) 2 – S (for a total of 2 S atoms) 2 – O 4 (for a total of 8 O atoms) The coefficient represents the number of molecules of that compound or atom needed in the reaction. If there is not a number, then “1” is understood to be in front of the formula. H 2 SO 4 Elements Hydrogen 2 atoms Sulfur: 1 atom Oxygen: 4 atoms 7 atoms total SubscriptĬoefficients A formula may begin with a number. Subscripts represent the number of atoms of the element that it is directly after.
Review: Chemical Formulas Shows the elements & number of atoms of each element in a molecule. Review: Element Symbols All elements are represented by a 1 or 2 letter symbol For example C = Carbon Ne = Neon O = Oxygen The symbols are shown on the periodic table Chemical Equations Putting chemical changes into wordsĪ chemical equation is a symbolic representation of a chemical reaction.Įquation Example: The burning of methane gas in oxygen is: CH 4 + 2 O 2 -> CO 2 + 2 H 2 O