Chapter 3 Lecture: Bonding, Ions, Ionic Compounds, and Polyatomic Ions

Vocabulary flashcards covering bonding types, ions, ionic compounds, polyatomic ions, and naming conventions from the lecture notes.

Ionic bonding

Bonding formed by the transfer of electrons from a metal to a nonmetal, producing oppositely charged ions held together by strong electrostatic attraction.

Covalent bonding

Bonding formed by sharing electrons between two nonmetals (or a metalloid with a nonmetal).

Ion

A charged species with an unequal number of protons and electrons.

Cation

Positively charged ion; forms when an atom loses electrons; has fewer electrons than protons.

Anion

Negatively charged ion; forms when an atom gains electrons; has more electrons than protons.

Octet rule

A main-group element is most stable when it has eight electrons in its outer (valence) shell.

Group 1A–3A cation charge (main-group metals)

For metals in groups 1A, 2A, and 3A, the cation charge equals the group number (e.g., 1A → +1, 2A → +2, 3A → +3).

Group 5A–7A anion charge (main-group nonmetals)

For nonmetals in groups 5A, 6A, and 7A, the anion charge equals 8 minus the group number (e.g., 7A → −1, 6A → −2, 5A—> -3).

Ionic compound

A compound composed of cations and anions held together by electrostatic attraction; overall charge is zero.

Write formula for an ionic compound (order)

Write the cation first, then the anion; use subscripts to balance charges; charges are not shown in the formula.

Charge balance rule

The sum of the charges of the cations and anions in an ionic compound must equal zero.

Calcium fluoride formula example

Calcium fluoride, CaF2, contains Ca2+ and two F− ions to balance a +2 charge.

Naming ionic compounds (main-group cations)

Cations from main-group metals are named from the element; if the metal has multiple charges, use either systematic (Roman numerals) or common name with -ous/-ic.

Systematic name for a cation

Cation name followed by Roman numeral in parentheses indicating its charge (e.g., iron(II)).

Common name suffixes for cations

Suffixes -ous for the lower charge and -ic for the higher charge (e.g., ferrous, ferric).

Anion naming with -ide

Replace the end of the element name with -ide for anions (e.g., chloride, oxide, sulfide).

Common metal ion names (examples)

Examples: Chromium(II) = chromous; Chromium(III) = chromic; Copper(I) = cuprous; Copper(II) = cupric; Iron(II) = ferrous; Iron(III) = ferric; Tin(II) = stannous; Tin(IV) = stannic; Mercury(I) = mercurous; Mercury(II) = mercuric.

Transition metals with variable charges

Some metals can form cations with more than one charge; the charge is indicated in systematic or common name.

Compounds of main-group metals naming rule

Name the cation then the anion; do not specify the charge or numbers of ions in the formula.

Copper(II) chloride vs cupric chloride

CuCl2; systematic copper(II) chloride; common name cupric chloride.

Deriving a formula from a name (tin(IV) oxide)

Identify the cation and anion and determine their charges; tin(IV) indicates Sn4+; oxide is O2−; two oxides balance +4; formula SnO2.

Polyatomic ion

A charged species that contains more than one atom.

Common polyatomic anions (examples)

Carbonate (CO3^2−), bicarbonate (HCO3−), acetate (C2H3O2−), cyanide (CN−), nitrate (NO3−), nitrite (NO2−), hydroxide (OH−), phosphate (PO4^3−), hydrogen phosphate (HPO4^2−), dihydrogen phosphate (H2PO4−), sulfate (SO4^2−), sulfite (SO3^2−).

Formulas with polyatomic ions

Writing formulas with polyatomic ions follows the same rules as for single-charged ions; balance charges; add parentheses if needed when multiple polyatomic ions appear.

Naming ionic compounds with polyatomic ions

Name the cation and then the polyatomic anion; charges are not shown in the name.

Zero overall charge in polyatomic formulas

In formulas with polyatomic ions, total charge sums to zero.

Sodium bicarbonate formula and name

NaHCO3; sodium bicarbonate.

Aluminum sulfate formula

Al2(SO4)3; contains Al3+ cations and sulfate anions.

Common body ions

Ca2+ in teeth/bones; Fe2+ in hemoglobin; Na+ and K+ in body fluids; Cl− in gastric juice; Mg2+ for nerve and muscle function.

Ionic compound properties

Ionic compounds are crystalline solids with very high melting/boiling points; soluble in water and, when dissolved, conduct electricity due to separated ions.

Covalent molecules

Molecules formed by covalent bonds between nonmetals; discrete units rather than extended lattices.

Bonding overview

Bonding is the joining of atoms to reach a noble gas configuration; ionic bonds from transfer; covalent bonds from sharing.

Sodium chloride example

NaCl is an ionic compound formed from a metal (Na) and a nonmetal (Cl).

Lithium oxide example

Li2O is an ionic compound comprising Li+ and O2−; two Li+ balance one O2−.

Sodium chloride dissolution

NaCl dissolves in water to form Na+ and Cl−, increasing solution conductivity.