Periodic Trends Explorer & Heatmap Laboratory

Visualize elemental gradients, effective nuclear charge variations, and thermodynamic periodic vectors across all 118 elements.

Across Period (Left → Right) Horizontal Axis

Increases Across Period (Left → Right): Effective nuclear charge (Z_eff) increases, drawing valence electrons closer.

Down Group (Top → Bottom) Vertical Axis

Decreases Down Group (Top → Bottom): Additional quantum shells n increase nuclear shielding and atomic distance.

Normalized Elemental Heatmap

18-Group Gradient Distribution

Low Intensity

High Intensity

1st Ionization Energy: Nitrogen > Oxygen Anomaly

Although Oxygen has higher Z (Z=8 vs Z=7), Nitrogen has a higher 1st ionization energy (1402 vs 1314 kJ/mol). Nitrogen possesses an exceptionally stable half-filled 2p³ subshell, whereas Oxygen has one paired electron in 2p⁴ experiencing inter-electronic repulsion.

Electron Affinity: Chlorine > Fluorine Anomaly

Fluorine has a smaller 2p orbital where electron density is extremely compact. Adding an extra electron causes significant inter-electronic repulsion, making Chlorine's larger 3p orbital more thermodynamically receptive (-349 kJ/mol vs -328 kJ/mol).

Lanthanide Contraction Effect

The poor shielding of 4f electrons across the Lanthanide series results in a steady shrinkage of atomic and ionic radii. Consequently, 4d and 5d transition congeners (e.g. Zr and Hf, Nb and Ta) have nearly identical radii and chemical behaviors.