A.6 Symbols, Formulas And Equations
- Chemical language used in oral and written communication has
been developed to represent atoms, elements, and compounds.
1. The “letters” in this language’s alphabet are Chemical
symbols.
- Each element is assigned a chemical symbol.
- Only the 1st letter of the symbol is capitalized; all other letters
are in lowercase. For example, C is the symbol for the element
carbon and Ca is the symbol for the element calcium.
2. “Words” in the language of chemistry are composed of “letters”
(symbols representing elements). Each “word” is a chemical
formula, which represents a different chemical compound.
- In the chemical formula of a compound, a chemical symbol
represents each element present.
- A Subscript (a small number written below the normal line
of letters) indicates how many atoms of the element.
Example, ammonia NH3. The subscript 3 indicates that each
ammonia molecule contains three hydrogen atoms. Ammonia
also contains one nitrogen atom. The subscript 1 is
understood in the absence of any subscript and is not
included in chemical formulas.
3. If formulas are words in the language of chemistry, then
Chemical equations can be regarded as chemical
“sentences”
- Chemical equations summarizes the details of chemical
reaction.
Chemical reactions entail the breaking and forming of
chemical bonds, causing atoms to become rearranged into new
substances. These new substances have different properties from
the original materials.
3 H2
+
N2
Hydrogen
Nitrogen
gas
gas
2 NH3
Ammonia
Reactants
Product
What was produced:
3 hydrogen molecules (H2), and one nitrogen molecule (N2)
reacted to produce (
) two molecules of ammonia (NH3).
Reactants(LS of arrow) are the original substances in a chemical
reaction.
Products(RS of arrow) are the new substance(s) formed from
the rearrangement of the reactant atoms.
Balanced total number of each type of atom is the same for
both reactants and products.