CH 2 (9/11) (PG 8-14)

A set of vocabulary-style flashcards covering key concepts from the video notes on molecular and ionic compounds, formulas, naming conventions, and related principles.

Compound

A pure substance formed when two or more elements combine in definite mass ratios (law of definite proportions); the elements' identities are not preserved in the compound.

Law of Definite Proportions

A principle stating that a compound contains elements in a fixed, definite ratio by mass.

Molecule

The smallest unit of a compound that retains the compound’s properties, especially in molecular compounds.

Molecular Formula

Shows the numbers and kinds of atoms present in a molecule.

Condensed Formula

Indicates how atoms are grouped together within the molecule.

Structural Formula

Shows the bonds (connections) between atoms in a molecule.

Molecular Model

A 3-D representation of a molecule.

Molecular Compounds

Compounds formed when non-metals combine; they exist as molecules.

Prefixes in Molecular Naming

Prefixes denote the number of each atom in a molecular formula.

Carbon Monoxide (CO)

A molecular compound with one carbon and one oxygen atom.

Carbon Dioxide (CO2)

A molecular compound with one carbon atom and two oxygen atoms.

Boron Trichloride (BCl3)

A molecule with one boron and three chlorine atoms.

Sulfur Dioxide (SO2)

A molecule with one sulfur atom and two oxygen atoms.

Silicon Tetrabromide (SiBr4)

A molecule with one silicon atom and four bromine atoms.

Tetraphosphorus Decaoxide (P4O10)

A molecule with four phosphorus atoms and ten oxygen atoms.

Getting the Formula From the Name

The process of deriving a molecular formula from the name, using prefixes to determine atom counts.

Ionic Compound

A compound formed from ions, typically a metal and a nonmetal, held together by ionic (electrostatic) bonds.

Ion

An atom or group with a net positive or negative charge.

Cation

A positively charged ion.

Anion

A negatively charged ion.

Electron Transfer

The process by which electrons are transferred between atoms to form ions.

Group-based Charges (General)

Metals tend to form cations; nonmetals tend to form anions, based on their group in the periodic table.

Group 1A-3A Cations

Main-group metals in these groups typically form cations with charges equal to their group numbers.

Group 7A-5A Anions

Nonmetals in these groups typically form anions with charges equal to (group number − 8).

Noble-Gas Electron Configuration

After electron transfer, atoms achieve the electron count of the nearest noble gas.

Monatomic Cation

Cation formed from a single element (e.g., Na+ is sodium ion).

Monatomic Anion

Anion formed from a single element (e.g., Cl− is chloride ion).

Naming Ionic Compounds Type I

Cation named first; anion second; monoatomic cations named after the element; monoatomic anions end in -ide with 'ion'.

Naming Ionic Compounds Type II

Transition metals can have multiple charges; Roman numerals indicate the metal’s charge.

Polyatomic Ion

A fixed group of atoms with a net charge that behaves as a unit in ionic compounds.

Oxyanion -ate/-ite; per-/hypo-

Oxyanions: more O atoms use -ate, fewer use -ite; per- and hypo- denote more or fewer O atoms.

Nitrate (NO3-)

A common oxyanion with three oxygens; ends with -ate.

Sulfate (SO4^2-)

Oxyanion with four oxygens; ends with -ate.

Phosphate (PO4^3-)

Oxyanion with four oxygens and a -3 charge; ends with -ate.

Charge Balance in Ionic Formulas

Ionic compounds are neutral overall; total positive charge equals total negative charge.

Parentheses in Formulas

Use parentheses around polyatomic ions when more than one of that ion is needed in the formula.

Sodium Chloride (NaCl)

Ionic compound composed of Na+ and Cl−; example of Type I ionic compound naming.

Magnesium Oxide (MgO)

Ionic compound with Mg2+ and O2−; exhibits a high melting point due to strong ionic bonds.

Coulomb’s Law (Electrostatic Forces)

The force between ions increases with charge magnitude and decreases with distance: F ∝ |q1 q2|/r^2.

Ionic Bond

The electrostatic attraction between a cation and an anion in an ionic compound.

Copper I/Ion and Copper II/Ion

Cu+ is copper(I) ion; Cu2+ is copper(II) ion.