Atomic Structure & Periodicity — 9 Terms Defined

p-Block Elements Atomic Structure & Periodicity Dimensionless The elements of groups 13 to 18, in which the outermost electrons progressively fill p orbitals. ns² np¹⁻⁶

Paramagnetism Atomic Structure & Periodicity BM Weak attraction into a magnetic field, shown by substances containing one or more unpaired electrons. μ = √(n(n+2)) BM

Pauli Exclusion Principle Atomic Structure & Periodicity Dimensionless The rule that no two electrons in an atom may have the same set of all four quantum numbers. n, l, mₗ, mₛ must differ

Period Atomic Structure & Periodicity Dimensionless A horizontal row of the periodic table, corresponding to one principal quantum number of the valence shell.

Periodic Law Atomic Structure & Periodicity Dimensionless The principle that the properties of the elements are periodic functions of their atomic numbers.

Periodic Table Atomic Structure & Periodicity Dimensionless The tabular arrangement of the chemical elements by increasing atomic number, grouping those with similar properties in vertical columns.

Plum Pudding Model Atomic Structure & Periodicity Dimensionless J. J. Thomson's 1904 model picturing the atom as a sphere of diffuse positive charge with electrons embedded within it.

Principal Quantum Number Atomic Structure & Periodicity Dimensionless The quantum number n that specifies the main energy level and average distance of an electron from the nucleus. E_n = −13.6 Z² / n² eV

Proton Atomic Structure & Periodicity u A positively charged subatomic particle found in the atomic nucleus, carrying a charge of +1 elementary unit. m_p = 1.6726 × 10⁻²⁷ kg