CHM2046 Final Exam – Vocabulary Flashcards

A comprehensive set of vocabulary flashcards summarizing key periodic trends, group chemistry, nuclear decay concepts, and acid–base fundamentals for CHM2046.

Ionization Energy

The energy required to remove an electron from a gaseous atom; increases across a period and up a group.

Electron Affinity

The energy change when an atom gains an electron; becomes more negative across a period.

Electronegativity

An atom’s ability to attract shared electrons; rises across a period and up a group.

Atomic Radius

The size of an atom; decreases across a period and increases down a group.

Metallic Character

Tendency to behave as a metal; increases down a group and decreases across a period.

Hydration Energy

Energy released when ions are solvated by water; larger for small, highly charged ions.

Covalent Oxide

Non-metal oxide that forms an acid when added to water.

Ionic Oxide

Metal oxide that forms a base when added to water.

Amphoteric Oxide

Oxide (e.g., Al2O3, BeO) that reacts with both acids and bases.

Group 1A (Alkali Metals)

Highly reactive metals; strongest reducing agents, reactivity Cs > K > Na > Li.

Downs Cell

Electrolytic cell that produces molten Na(l) and Cl2(g) from molten NaCl.

Peroxide (O2²⁻)

Oxygen species stabilized by Na⁺; product Na2O2 from 2 Na + O2.

Superoxide (O2⁻)

Larger O2⁻ ion stabilized by K⁺; KO2 forms from K + O2, used in SCUBA rebreathers.

Reducing Agent

Species that donates electrons; strongest in Group 1A, especially Cs and K.

Group 2A (Alkaline Earth Metals)

Reactive metals forming strong bases; Ca reacts with cold water, Mg with steam.

Electron-Deficient (Boron)

Having fewer than eight valence electrons; boron often forms 6-electron species.

Bridge Bond

Three-center, two-electron bond found in B2H6 and Al compounds.

Lewis Acid

Electron-pair acceptor; BF3 acts as one when it binds NH3.

Amphoterism

Ability to react with both acids and bases, characteristic of Al2O3 and BeO.

Diagonal Relationship

Similarity between elements diagonally adjacent in the periodic table, e.g., Be and Al.

Graphite

sp2-hybridized carbon allotrope that conducts electricity.

Diamond

sp3-hybridized carbon allotrope that is an electrical insulator.

Graphene

Single layer of sp2-hybridized carbon atoms with high conductivity.

Ostwald Process

Industrial route to HNO3: 3 NO2 + H2O → 2 HNO3 + NO.

Contact Process

Industrial formation of H2SO4: SO3 + H2O → H2SO4.

Alpha Decay

Emission of a 4He2 nucleus; common for Z > 83, lowest penetration.

Beta Decay (β⁻)

Emission of an electron (0e⁻1) to lower N/Z when neutrons are too many.

Positron Decay (β⁺)

Emission of 0e⁺1 to raise N/Z when neutrons are too few; same net effect as EC.

Electron Capture (EC)

Nucleus captures an inner electron; converts a proton to a neutron, like β⁺ decay.

Gamma Radiation

High-energy photons with no charge; highest penetration, blocked by lead.

Band of Stability

Region of stable N/Z ratios; outside it, nuclei undergo decay to become stable.

Half-Life (t1/2)

Time for half a radioactive sample to decay; for first-order, t1/2 = ln 2 / k.

Curie (Ci)

Unit of radioactivity equal to 3.7 × 10¹⁰ disintegrations per second.

Becquerel (Bq)

SI unit of radioactivity; 1 disintegration per second.

Gray (Gy)

Absorbed radiation dose of 1 joule per kilogram.

Sievert (Sv)

Biological effect dose; 1 Sv = 0.01 rem.

Acidic Oxide

Same as covalent oxide; forms acids in water (e.g., SO3 → H2SO4).

Basic Oxide

Ionic oxide that yields a base in water (e.g., CaO → Ca(OH)2).

Neutral Ions

Ions that do not influence pH: Group 1A cations, Ca2+, Sr2+, Ba2+, Cl⁻, Br⁻, I⁻, NO3⁻, ClO4⁻.

Ka (Acid Dissociation Constant)

Quantifies acid strength: Ka = [H3O⁺][A⁻]/[HA].

Kb (Base Dissociation Constant)

Quantifies base strength: Kb = [HB⁺][OH⁻]/[B].

Henderson–Hasselbalch Equation

pH = pKa + log([A⁻]/[HA]); relates buffer pH to acid/base ratio.

Buffer Solution

Mixture of weak acid and its conjugate base (or vice-versa) that resists pH change.

Water Auto-ionization

Self-ionization of water: Kw = [H3O⁺][OH⁻] = 1.0 × 10⁻¹⁴ at 25 °C.

Ionizing Power

Ability of radiation to produce ions; highest for alpha, then beta, lowest for gamma.

Penetrating Power

Depth radiation can travel; greatest for gamma, then beta, least for alpha.