Chapter 3 – Ionic Compounds (Fundamentals of GOB Chemistry)

A comprehensive set of Q&A flashcards covering ion formation, periodic trends, ionic nomenclature, formulas, properties, and introductory acid–base concepts from Chapter 3 (Ionic Compounds).

What is an ion?

An atom (or group of atoms) that has gained or lost electrons and therefore carries a net electric charge.

What name is given to a positively-charged ion formed by electron loss?

Cation.

What name is given to a negatively-charged ion formed by electron gain?

Anion.

State the octet rule for main-group elements.

Atoms tend to undergo reactions that leave them with eight valence electrons, achieving a noble-gas electron configuration.

How do alkali metals (Group 1A) satisfy the octet rule?

They lose their single valence ns1 electron to form 1+ cations with a noble-gas configuration.

Write the symbol for a sodium cation.

Na⁺

Write the symbol for a chloride anion.

Cl⁻

What charge is normally adopted by Group 1A metal ions?

+1

What charge is normally adopted by Group 2A metal ions?

+2

What charge do Group 3A metals commonly exhibit?

+3 (e.g., Al³⁺).

What charge do Group 5A nonmetals normally adopt when they form ions?

−3

What charge do Group 6A nonmetals normally adopt when they form ions?

−2

What charge do Group 7A (halogen) ions have?

−1

How can you predict the anion charge of a main-group non-metal?

Anion charge = 8 − (group number).

Define ionization energy (IE).

The energy required to remove one electron from a gaseous atom.

Describe the periodic trend for ionization energy across a period.

IE increases from left to right across a period.

Describe the periodic trend for ionization energy down a group.

IE decreases down a group.

Why is potassium more reactive than sodium or lithium?

Its lower ionization energy makes it easier to lose its valence electron.

Define electron affinity (EA).

The energy released when a gaseous atom gains an electron to form an anion.

How does electron affinity generally change across a period?

EA increases (becomes more negative) from left to right.

Which family has the largest electron affinities?

The halogens (Group 7A).

Differentiate Type I and Type II ionic compounds.

Type I contain main-group metal cations with fixed charge; Type II contain metals (usually transition metals) that can exhibit more than one charge.

What is the naming rule for Type I ionic compounds?

Cation name (element) + anion name ending in –ide (or polyatomic name), without indicating charge.

How do you name Type II metal cations using the Stock system?

Give the metal name followed by its charge in Roman numerals in parentheses, then the anion name.

Give the Stock and common names for FeCl₂.

Iron(II) chloride (ferrous chloride).

Give the Stock and common names for FeCl₃.

Iron(III) chloride (ferric chloride).

How are monoatomic anions named?

Replace the element ending with –ide and add the word ion (e.g., oxide ion, sulfide ion).

Define a polyatomic ion.

A charged species composed of two or more covalently bonded atoms acting as a single ion.

Provide the formula and charge of the sulfate ion.

SO₄²⁻

Provide the formula and charge of the hydroxide ion.

OH⁻

Explain how to write a neutral formula for an ionic compound.

Combine cations and anions in the smallest whole-number ratio that yields a total charge of zero.

What is a formula unit?

The simplest whole-number ratio of ions that represents an ionic compound’s composition.

State three characteristic physical properties of ionic compounds.

High melting/boiling points, brittleness (shatter when struck), and electrical conductivity when molten or in aqueous solution.

Why do aqueous ionic solutions conduct electricity?

Because the ions are free to move and carry charge.

Define an acid in Arrhenius terms.

A substance that provides H⁺ (protons) in water.

Define a base in Arrhenius terms.

A substance that provides OH⁻ ions in water.

Give an example of a monoprotic acid and its formula.

Hydrochloric acid, HCl.

Give an example of a diprotic acid and its formula.

Sulfuric acid, H₂SO₄.

Give an example of a triprotic acid and its formula.

Phosphoric acid, H₃PO₄.

How are oxyacids named when the anion ends in –ate?

Replace –ate with –ic and add the word acid (e.g., nitrate → nitric acid).

How are oxyacids named when the anion ends in –ite?

Replace –ite with –ous and add the word acid (e.g., nitrite → nitrous acid).

What is the acid corresponding to the nitrate ion (NO₃⁻)?

Nitric acid (HNO₃).

Write the formula for sodium hydroxide.

NaOH

Write the formula for barium hydroxide and state how many OH⁻ ions it releases.

Ba(OH)₂; it provides two hydroxide ions per formula unit.

What is meant by a Type I metal cation?

A main-group metal whose ionic charge does not vary (e.g., Na⁺, Mg²⁺).

What two naming endings are used in the older system for variable-charge metals?

-ous for the lower charge and –ic for the higher charge (e.g., cuprous / cupric).

Why do transition metals often form more than one cation?

They can lose valence-shell s electrons and one or more d electrons, so the octet rule does not strictly apply.

Give the Stock name for Cu⁺ and Cu²⁺.

Copper(I) ion and copper(II) ion, respectively.

What common ions play vital roles inside cells (name two)?

Examples: K⁺ (regulates heartbeat and insulin release) and Mg²⁺ (enzyme cofactor, energy generation).