Fundamental Principles of Atomic Structure and Chemical Bonding

Atomic Structure and Quantum Theory

• Isotopes: Atoms of the same element with identical chemical properties but different atomic masses.
• Planck's Quantum Theory: Energy emitted by a body through radiation of a specific frequency is a multiple of a basic energy quantity called a quantum (E = h · v).
• Particle Theory: Light consists of particles (photons) with energy defined by E = h · v.
• Bohr Model: Electrons occupy specific energy levels surrounding the nucleus, defined by the principal quantum number. When an atom absorbs or emits energy, it does so in discrete amounts equal to h · v.
• Quantum-Mechanical Model: Electrons exhibit both wave and particle properties. It is impossible to accurately determine the precise position of an electron within an atom.

Electronic Configuration and Orbital Rules

• Electronic Configuration: The distribution of electrons of an atom in orbitals.
• Aufbau Principle (Rule of Construction): The fundamental electronic configuration is obtained by placing electrons one by one into available orbitals in order of increasing energy.
• Pauli Exclusion Principle: No two electrons in the same atom can have the same four quantum numbers.
• Hund's Rule of Maximum Multiplicity: When electrons occupy degenerate orbitals of the same energy, they fill different orbitals with parallel spins as much as possible.

Chemical Properties and Bonding

• Electronegativity: The relative tendency of an atom to attract electrons from other atoms to which it is bonded.
• Noble Gases: Elements defined by their chemical inertia and resistance to forming compounds.
• Valence Electrons: Electrons responsible for the differences in properties between elements in a period.
• Shielding Effect: The repulsion between electrons that decreases the attraction of the nucleus and affects the state of electrons in the atom.

Chemical Formulas and Nomenclature

• Chemical Formula: A symbolic expression of the composition and structure of a chemical substance.
• Empirical Formula: Expresses the minimum ratio in which atoms or ions are present in a chemical substance.
• Molecular Formula: Expresses the actual number of atoms of each element present in a molecule of a chemical substance.
• Inorganic Compounds: All chemical compounds except those based on carbon.
• Chemical Valence: The combining capacity of an atom of an element to form a chemical compound.
• Oxidation Number: The electric charge an atom would possess if the entire compound were constituted of positive and negative ions. It represents combining ability and is written above the element symbol with the appropriate sign.
• Ionic Charge: The charge (+ or -) acquired by an atom or group of atoms when they lose or gain electrons.