Thorium commonly forms Th4+ in introductory ionic compounds.
| Element | Thorium |
|---|---|
| Symbol | Th |
| Atomic number | 90 |
| Common ionic charge | +4 |
| Common ions | Th4+ |
Images are used as visual references; charge rules still depend on the compound.
Thorium is [Rn]6d2 7s2. All four outer electrons leave for the radon core, and the resulting Th4+ — big, highly charged, with no f electrons — behaves like a super-sized Zr4+. Its oxide ThO2 has the highest melting point of any binary oxide (3,390 °C).
This is a classroom reference range, not an exhaustive list of all oxidation states.
Assuming everything radioactive is fiercely so. Th-232's half-life is 14 billion years — older than the universe is not required reading for an element to seem 'stable' on human timescales. Handling concerns center on ingestion and decay daughters, not the gentle parent.
Th4+ with O2- crosses to ThO2 — the gas-mantle compound that lit streets and campsites for a century: heated ThO2 (with a cerium pinch) glows brilliant white, no electricity required.
Thorium chloride
Th4+ balances chloride ions.
Thorium oxide
Thorium can form oxides where total positive and negative charge balances.
Th-232 absorbs a neutron and beta-decays into fissile U-233. In molten-salt designs the thorium circulates as ThF4 (Th4+ in fluoride melt) — the +4 chemistry is the fuel plumbing; the nucleus is the payload.
Mid-century 'thoriated' glass used ThO2 for its high refractive index — sharp optics with a whisper of radioactivity that collectors still measure today. The Th4+ sits inert in the glass network.
Crustal thorium (~10 ppm) rivals lead and beats tin — 'rare' it is not. Its energy content in theory exceeds all uranium and fossil reserves combined; engineering, not chemistry, is the barrier.
Combine positive and negative ions so the total charge is zero — or let the ionic compound calculator do the crossing for you. The full chart lives on the periodic table with charges.
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