Every number here has a reason.
Click any element to see its properties explained, not just listed. Electronegativity, ionization energy, electron affinity, and oxidation-state flexibility are each traced to the atomic structure driving them: effective nuclear charge, shielding, radius, shell and subshell configuration. When an element breaks its period's trend, the page names which of these features is responsible.
statistical period/group trend anomaly electron configuration breaks the simple Aufbau filling rule
s-block p-block d-block f-block
Period & group trends
See how a property changes across a period or down a group, with the same reasoning engine as the compare tool applied to every step.
Compare two species
Compare any two elements, or an element against one of its own ions (e.g. Na vs Na+), and see exactly what structural quantities changed.
Estimate a diatomic bond
Enter two element symbols to estimate the bond between them from electronegativity difference. Bond order (MO theory) is only estimated for a homonuclear pair within H–Ne, where the simple model is actually valid — see the note below the result for anything else.