Chemistry Section 3: Mole Ratios, Chemical Formulae and Chemical Equations

Vocabulary flashcards covering chemical nomenclature, laws of chemical combination, types of equations, and stoichiometric calculations based on the Section 3 lecture notes.

Oxidation number

The charge of an ion in a compound, or the number of electrons gained or lost by an atom when forming a compound.

Empirical formula

The simplest whole number ratio of atoms of each element present in a compound.

Molecular formula

A formula that shows the actual number of atoms of each element in the simplest unit of a substance.

Structural formula

A formula that shows the arrangement of atoms and how they are bonded to each other in a molecule.

Prefix

A word part used in naming to indicate the number of atoms of an element in a compound (e.g., mono-, di-, tri-, tetra-).

Suffix

A word part used in naming to indicate the type of compound or ion (e.g., -ide, -ate, -ite).

Reactant

A substance present at the start of a chemical reaction that takes part in the reaction itself.

Product

A substance formed as a result of a chemical reaction.

Stoichiometry

The relationship between the quantities of reactants and products in a chemical reaction.

Coefficient

The number placed in front of a chemical formula in a balanced equation to indicate the relative number of moles of that substance.

Mole ratio

The ratio of the number of moles between two or more substances that take part in a chemical reaction.

Yield

The amount or mass of product obtained from a chemical reaction.

Actual yield

The amount or mass of product actually obtained from a reaction in practice.

Theoretical yield

The maximum amount or mass of product that could be produced from a given amount of reactant, based on stoichiometric calculations.

Percent yield

The ratio of the actual yield to the theoretical yield, expressed as a percentage: $\frac{Actual\,yield}{Theoretical\,yield} \times 100$

Limiting reagents

The reactants in a chemical reaction that are consumed completely, thereby limiting the mass of the product formed.

Excess reagents

The reactants that are left over when a chemical reaction has stopped.

Simple Binary Compounds (Ionic)

Compounds named by listing the cation (metal) first, followed by the anion (non-metal) with the suffix changed to '-ide.'

Law of Conservation of Mass

The law stating that mass is not created or destroyed in a chemical reaction; therefore, the total mass of reactants equals the total mass of products.

Law of Definite Proportions

The law stating that a given chemical compound always contains its component elements in a fixed ratio by mass.

Law of Multiple Proportions

The law stating that when two elements form more than one compound, the ratios of the masses of the second element that combine with a fixed mass of the first element are ratios of small whole numbers.

Chemical formula

An expression which shows the chemical composition of a compound in terms of the symbols of the atoms involved.

Molecular Formula Relationship

The formula to derive a molecular formula from an empirical formula: $Molecular\,formula = (Empirical\,formula)n$, where $n = \frac{Molecular\,mass}{Empirical\,formula\,mass}$.

Percentage Composition

The percent by mass of an element in a compound calculated as: $\frac{Relative\,atomic\,mass \times Number\,of\,atoms}{Relative\,molecular\,mass} \times 100$

Combustion

A chemical reaction in which a substance reacts with oxygen to produce oxides and generate heat.

Synthesis

A reaction where two or more simple substances combine to form a single, more complex product ($A + B \rightarrow AB$).

Displacement reaction

A reaction in which one atom or ion in a reactant is replaced by another atom or ion of another element.

Decomposition

A chemical reaction in which a single reactant breaks down into two or more simpler substances, often under conditions of heat, light, or a catalyst.

Ionic equation

A chemical equation involving at least one ionic species as a reactant or product.

Spectator ions

Ions that exist in a chemical equation but are not involved in the overall reaction.

Molar Volume ($V_m$) at s.t.p.

The volume occupied by 1 mole of any gas at standard temperature and pressure, which is $22.4\,dm^3/mol$.

Parts per million (ppm)

A unit of concentration calculated in this context as: $g\,dm^{-3} \times 1000$.