Atomic Structure and Nuclear Chemistry

Comprehensive vocabulary flashcards detailing atomic theories, quantum models, subatomic particle properties, isotopes, and medical applications of radioactivity based on the lecture material.

Dalton's Atomic Model ("Billiard Ball" Model)

A model formulated in 1803 proposing that matter is composed of microscopic, indivisible, and indestructible spherical atoms that combine in simple whole-number ratios to form compounds, without recognizing subatomic particles, isotopes, or radioactivity.

Rutherford's Gold Foil Experiment

An experiment where alpha particles were directed at a thin sheet of gold; while most passed through undeflected, approximately 1 in 8,000 was deflected by an angle greater than 90^\flavors90^\text{o}$$, proving the existence of a dense, positively charged nucleus surrounded by mostly empty space.

Atomic Instability Problem (Rutherford Model)

A fundamental limitation of Rutherford's model under classical electromagnetism, which dictates that an accelerating charged particle (such as an orbiting electron) must continuously lose energy and spiral into the nucleus.

Energy Quantization (Bohr Model)

The concept introduced by Niels Bohr in 1913 applying Planck's quantum theory, establishing that atomic electrons do not radiate energy continuously but instead occupy fixed, quantized stationary orbits corresponding to discrete energy levels.

Ground State (Stato Fondamentale)

The lowest possible energy level that an electron can occupy in an atom, located closest to the nucleus.

Excited State (Stato Eccitato)

An unstable, higher-energy orbit reached when an electron absorbs energy (such as a photon); it lasts approximately $10^{-8}\,\text{s}$ before the electron returns to the ground state while emitting a photon of identical energy.

De Broglie's Hypothesis

The theory proposing that moving electrons possess wave-particle duality and behave as standing waves, remaining stable without energy loss only when their orbits equal an integer multiple of their wavelength ($\lambda$).

Atomic Orbital (Schrödinger Model)

A three-dimensional spatial region derived from wave equations where there is a high probability of finding an electron, replacing the classical concept of fixed planar orbits.

Wave Function ($\psi$)

The mathematical solution to Schrödinger's wave equation describing the probability density of an electron in three-dimensional space, characterized by three quantum numbers ($n, l, m_l$) that determine its energy and spatial orientation.

Heisenberg Uncertainty Principle

A quantum principle stating that it is physically impossible to simultaneously measure both the exact position and the exact momentum of an electron.

Subatomic Particle Masses

The measured masses of the fundamental particles in atomic mass units (amu): a proton is equal to $1\,\text{amu}$, a neutron is $1.008\,\text{amu}$, and an electron is approximately $\frac{1}{1836}\,\text{amu}$.

Mass Defect (Difetto di Massa)

The difference between the total sum of the individual masses of separate nucleons (protons and neutrons) and the actual, lower mass of the bound nucleus, which accounts for nuclear binding energy.

Isotopes

Atoms of the same chemical element that possess the identical atomic number of protons ($Z$) but differing mass numbers ($A$) due to a different number of neutrons.

Isotopes of Hydrogen

The three isotopic variants of hydrogen: protium ($1\,\text{proton}$, $0\,\text{neutrons}$, $A = 1$), deuterium ($1\,\text{proton}$, $1\,\text{neutron}$, $A = 2$), and tritium ($1\,\text{proton}$, $2\,\text{neutrons}$, $A = 3$).

Average Atomic Mass Formula

The weighted average calculation of an element's atomic mass based on its naturally occurring isotopic abundances: $\text{atomic mass} = \frac{MA_1 \cdot \%_1 + MA_2 \cdot \%_2 + \dots}{100}$.

Positron Emission Tomography (PET)

A diagnostic imaging technique that introduces a positron-emitting radioisotope (such as Fluorine-18) into the body to trace and evaluate metabolic processes in three dimensions.

Positron-Electron Annihilation

The interaction that occurs during PET imaging when an emitted positron encounters a tissue electron, resulting in their mutual destruction and the simultaneous emission of two gamma photons in opposite directions.

Acute Radiation Syndrome Dose Threshold

An acute whole-body ionizing radiation exposure ranging between $1\,\text{Sv}$ and $2\,\text{Sv}$ that produces clinical acute radiation sickness.