Reference · Valence Table

The Valence Table

The periodic table as a charge machine: an element's group sets its common ion charge, and a cation and anion combine in whatever ratio makes the compound neutral. The grid is the full periodic table — all 118 elements in their standard IUPAC positions, with the lanthanides and actinides as the two detached f-block rows. Depth for the common elements (a sourced ion and every machine-verified salt) and breadth for the rest (name, position, and whatever properties are sourced — an honest gap where a value isn't). Four modes: Explore the grid through five lenses (each with its pattern, its why, and its exceptions), graph the Trends across a period or down a group, build any salt in the Formula builder (every pair machine-verified and named), and compare two elements in Bonding (ΔEN → polarity, with OpenStax's own caution). Values are sourced; the salts are assembled by charge crossover and re-checked atom-by-atom. Calcium and sodium are highlighted — the ions of the precipitation lesson. Drills on this data live in the periodic-trends gym.

Lens:

spdf 16 of 118 carry a common monatomic ion

La and Ac sit in group 3; the 28 f-block elements (58–71 lanthanides, 90–103 actinides) are drawn as the two detached rows, as on a standard periodic table. A corner mark flags the 16 elements that carry a common ion and full charge-balance coverage — click one for its salts. Every other cell shows the sourced values it has and nothing it doesn't.

Common ion charge data-sourced (openstax-chemistry-2e) interpretive — story, not proof

What pattern?: Main-group metals form cations, nonmetals anions: group 1 → +1, group 2 → +2, group 13 → +3; group 15 → −3, group 16 → −2, group 17 → −1. The noble gases form no simple ion.
Why (the story): Atoms bond toward the nearest noble-gas electron count. A metal sheds its few valence electrons to expose a full inner shell; a nonmetal gains the few it lacks — the charge is just how many electrons moved.
Exceptions: Transition metals (Fe and Cu here) hold more than one common charge — the Stock numeral in a name says which. Hydrogen sits in group 1 but is no metal; it shares electrons more often than it transfers them.
Where it shows up: Formula writing (charge crossover), nomenclature (iron(II) vs iron(III)), and predicting the products of double replacement.

Polyatomic ions — click one:

calcium

Z = 20 · 40.078 g/mol · s-block · group 2, period 4 · 2 valence e⁻

Common ion: $\mathrm{Ca}^{2+}$ (calcium ion) — charge 2+. rule-sourced (openstax-chemistry-2e)

Main-group metals lose electrons to a full shell (group 1 → +1, group 2 → +2); nonmetals gain them (group 16 → −2, group 17 → −1). Charges below are sourced, not inferred — the pattern is a guide, the data is the authority.

Periodic properties data-sourced

Electronegativity1.00Pauling · allred-1961-electronegativity

Covalent radius176 pmcordero-2008-covalent-radii

First ionization energy589.8 kJ/molnist-ionization-energies

Neutral formulas from charge balance verified

Ca²⁺ + C₂H₃O₂⁻ → $\mathrm{Ca(C_{2}H_{3}O_{2})_{2}}$ calcium acetate 1×(+2) + 2×(−1) = 0

Ca²⁺ + CO₃²⁻ → $\mathrm{CaCO_{3}}$ calcium carbonate 1×(+2) + 1×(−2) = 0

Ca²⁺ + Cl⁻ → $\mathrm{CaCl_{2}}$ calcium chloride 1×(+2) + 2×(−1) = 0

Ca²⁺ + F⁻ → $\mathrm{CaF_{2}}$ calcium fluoride 1×(+2) + 2×(−1) = 0

Ca²⁺ + H₂PO₄⁻ → $\mathrm{Ca(H_{2}PO_{4})_{2}}$ calcium dihydrogen phosphate 1×(+2) + 2×(−1) = 0

Ca²⁺ + HCO₃⁻ → $\mathrm{Ca(HCO_{3})_{2}}$ calcium hydrogen carbonate 1×(+2) + 2×(−1) = 0

Ca²⁺ + HPO₄²⁻ → $\mathrm{CaHPO_{4}}$ calcium hydrogen phosphate 1×(+2) + 1×(−2) = 0

Ca²⁺ + NO₃⁻ → $\mathrm{Ca(NO_{3})_{2}}$ calcium nitrate 1×(+2) + 2×(−1) = 0

Ca²⁺ + N³⁻ → $\mathrm{Ca_{3}N_{2}}$ calcium nitride 3×(+2) + 2×(−3) = 0

Ca²⁺ + OH⁻ → $\mathrm{Ca(OH)_{2}}$ calcium hydroxide 1×(+2) + 2×(−1) = 0

Ca²⁺ + O²⁻ → $\mathrm{CaO}$ calcium oxide 1×(+2) + 1×(−2) = 0

Ca²⁺ + PO₄³⁻ → $\mathrm{Ca_{3}(PO_{4})_{2}}$ calcium phosphate 3×(+2) + 2×(−3) = 0

Ca²⁺ + SO₄²⁻ → $\mathrm{CaSO_{4}}$ calcium sulfate 1×(+2) + 1×(−2) = 0

Ca²⁺ + S²⁻ → $\mathrm{CaS}$ calcium sulfide 1×(+2) + 1×(−2) = 0

The subscripts aren't guessed — they're whatever makes the total charge zero (charge crossover), then re-checked atom-by-atom. Try any pair in the Formula builder.