CHM2046 Exam 4 – Periodic Trends and Main-Group Chemistry

Vocabulary flashcards covering periodic trends, main-group element properties, industrial processes, and key chemical behaviors to prepare for CHM2046 Exam 4.

Ionization Energy Trend

Increases as you move up and to the right across the periodic table (same as effective nuclear charge).

Electron Affinity Trend

Becomes more negative (greater magnitude) up and to the right; nonmetals have more negative EA than metals.

Atomic Size Trend

Decreases as you move up and to the right across the periodic table.

Periodic Reactivity Hotspots

Highest at both ends of the table: alkali metals (Group 1A) and halogens (Group 7A), excluding noble gases.

Electronegativity Trend

Increases up and to the right, with noble gases omitted.

Covalent Oxide Trend

Prevalence of covalent oxides increases up and to the right on the periodic table.

Ionic Oxide Trend

Prevalence of ionic oxides increases down and to the left on the periodic table.

Metallic Character Trend

Increases as you move down and to the left across the periodic table.

Non-metallic Character Trend

Increases as you move up and to the right across the periodic table.

Hydration Energy

Energy released when ions dissolve in water; higher ionic charge or smaller radius gives more exothermic hydration energy.

White Phosphorus (P4)

Tetrahedral P4 molecule with no central atom; most stable allotrope mentioned in the notes.

Nitrogen vs. Phosphorus States

N2 is a gas due to small size and a strong triple bond; P4 is a solid because larger atoms are linked by single bonds.

Cyclic Silicate Formula

(SiO3)n – rings of tetrahedral SiO3 units.

Carbothermic Reduction of SiO

SiO + 2 C → Si + 2 CO at about 3000 °C.

HF Boiling Point

Unusually high because of strong hydrogen bonding between HF molecules.

Sulfuric Acid on Sugar

Concentrated H2SO4 dehydrates table sugar, leaving a porous carbon mass.

Fluorine with Noble Gases

F2 can react with Xe and Kr to form interhalogens such as XeF2, XeF4, XeF6.

Alkali Metal Properties

Group 1A metals have a +1 oxidation state, comparatively high IE/EN for metals, and react vigorously with water to form hydroxide and H2.

Ostwald Process

Industrial synthesis of HNO3 from NH3 and O2 via NO and NO2 intermediates.

Fluorine Oxidation State

Always –1 in compounds.

Hydrogen Isotopes

Protium (¹H), deuterium (²H or D), and tritium (³H or T).

Types of Hydrides

Ionic (e.g., NaH), covalent (e.g., CH4, NH3), and polymeric/metalloid (e.g., (BeH2)x).

Hydrogen Bonding

Strong intermolecular force when H is bonded to F, O, or N.

Hydride Reaction with Water

H⁻ + H2O → H2 + OH⁻; e.g., LiH + H2O → LiOH + H2.

Graphite

Black, soft, layered allotrope of carbon that conducts electricity.

Diamond

Clear, extremely hard, three-dimensional network allotrope of carbon; electrical insulator.

Fullerene (C60)

Spherical "buckyball" allotrope of carbon shaped like a soccer ball.

Alkali Metals with Water

2 M + 2 H2O → 2 MOH + H2; highly exothermic and often ignites hydrogen.

Hydrogen Gas as Reductant

H2 reduces many metal ions to metals and is oxidized to H⁺.

Silicate Tetrahedron

Basic mineral unit SiO4⁴⁻ that links into chains, sheets, or 3-D frameworks.

Contact Process for H2SO4

S + O2 → SO2 → SO3 → H2SO4 through catalytic steps.

Uses of Phosphoric Acid

Fertilizers, food additive, tart flavor in soda, paint stripper.

Nitric Acid in Redox

HNO3 is a strong oxidizing agent and is reduced in many reactions.

Diagonal Relationship

Li–Mg, Be–Al, B–Si pairs share similar properties due to size and charge density.

Li and Mg Similarities

Form unstable nitrides, decomposable hydroxides/carbonates, and polar Li–C & Mg–C bonds.

Be and Al Similarities

Both exhibit amphoteric oxides, high melting points, and bridged hydrides/halides; ions are small and highly charged.

Unique Chemistry of Lithium

Forms Li2O and Li3N in air, makes covalent Li–C bonds, and its salts show low solubility.

Sodium Production (Downs Cell)

Electrolysis of molten NaCl yields liquid Na metal and Cl2 gas.

Industrial Potassium Production

Distillation of molten KCl in the presence of Na vapor produces K metal.

Oxides of Na and K

Na forms Na2O (limited O2) and Na2O2 (excess O2); K forms KO2 (superoxide) in air.

Magnesium with Water

No reaction with cold water; reacts slowly with steam to produce Mg(OH)2 and H2.

Calcium with Water

Reacts with cold water to form Ca(OH)2 and H2 gas.

Covalent Behavior of Beryllium

Small size and high second ionization energy favor covalent bonding in Be compounds.

BeCl2 Structure vs. Temperature

High-T gas: linear sp-hybrid; low-T solid: polymeric with bridging Cl atoms for octet completion.

Group 2A Oxide Basicity

Alkaline-earth oxides are strong bases that neutralize acidic oxides to form salts.

Solubility of Group 2A Salts

Many fluorides, sulfates, carbonates, and phosphates are sparingly soluble due to high lattice energy.

Alkali Metal Physical Properties

Soft, body-centered cubic metals with low melting points and densities; strong reducing agents.

Exothermic Na–Water Reaction

2 Na + 2 H2O → 2 NaOH + H2(g); heat often ignites the hydrogen.