M2 Periodic Trends Z = 1..118

Periodic Explorer

Deep multivariable trend curves, 2D/3D scatter plots, multi-element comparison matrices, and Wikipedia-grade isotopic dossiers.

Periodic Trends Guide

Effective Nuclear Charge (Zeff): Net positive charge experienced by valence electrons ($Z_{eff} = Z - S$). Increases across periods, causing atomic radius contraction.

Atomic & Covalent Radii: Decreases from Group 1 to Group 18 across a row due to higher $Z_{eff}$; expands down groups due to principal quantum shell additions ($n$).

First Ionization Energy: Energy required to remove the outermost electron. Exhibits peaks at noble gases and inflections at subshell completions ($s^2$, $p^3$).

Electronegativity (Pauling): Tendency of an atom in a molecule to attract shared electron pairs. Fluorine is maximum ($3.98$), Francium/Cesium minimum ($0.7$).

Crystal Lattice Types: Solid state atomic geometries including Face-Centered Cubic (FCC, 74% APF), Body-Centered Cubic (BCC, 68% APF), and Hexagonal Close-Packed (HCP).

Isotope Systematics: Stable vs radioactive nuclides governed by the Valley of Stability and N/Z ratios.

Element Quick Finder

Trend Property (Y-Axis)

Element Subset / Scope

Period Boundary Dividers Connect Smooth Trendline

Open Full 18-type Periodic Table

Atomic Radius Trend

vs Atomic Number (Z = 1..118)

Min: 28 pm Max: 225 pm

Periodic Pattern

Decreases across row, expands down

Period 2 Gradient

152 pm (Li) -> 38 pm (F)

Period 3 Gradient

186 pm (Na) -> 99 pm (Cl)

Inflection Anomalies

Lanthanide Contraction (4f)

Multi-Axis Radar Comparison

Quantitative Property Matrix

79 Au

Gold

Transition Metal

Gold is a dense, soft, malleable, ductile, bright yellow metal, prized since antiquity for coinage and jewelry.

196.967 amu

d-block | Period 6 | Group 11

Ancient (c. 6000 BC)

Bohr Electron Shells (K-Q)

2, 8, 18, 32, 18, 1

Crystal Lattice

Face-Centered Cubic (FCC)

Space Group: Fm-3m (225)

Coordination: 12

Packing Fraction: 74.0%

Lattice Constant: 407.82 pm

Principal Isotopes

Isotope	Abundance	Half-Life	Decay