Nuclear playground

Chemistry rearranges electrons; nuclear processes change the nucleus. Pick a nuclide, test decay modes against the conservation laws, and run the decay law. Balance tells you a process is allowed by the bookkeeping — not that it happens.

Stableβ⁻β⁺ECαβ-stability line (rule of thumb)N = ZDots are the bundled reference nuclides only · click anywhere to choose a nuclide

Decay chain (bundled reference data)

α →β⁻ →β⁻ →α →α →α →α →α →β⁻ →β⁻ →α →β⁻ →β⁻ →α →

Ends at a stable nuclide after 14 steps. Each step follows only the dominant reported mode; branching is ignored.

Nuclear equation checker

Write nuclides as U-235, 235U or ²³⁵U; particles as n, p, alpha, e-, e+, nu, anti-nu, gamma, d, t.

²³⁵U + n → ¹⁴¹Ba + ⁹²Kr + 3 n

Conserved	Left	Right
Nucleon number A	236	236	✓
Charge Z (in e)	92	92	✓
Lepton number L	0	0	✓

Balanced: nucleon number, charge and lepton number are all conserved. Energy (Q-value) is not checked.

ElementMass no. A

²³⁸UUranium-238

Protons / neutrons: 92 / 146
N/Z: 1.59
Half-life: 4.468 × 10⁹ y
Reported decay: α

Rule of thumb: Close to the stability line for this mass number, so a stable or long-lived nuclide is plausible. Nothing guarantees it. Heavy nuclei beyond Pb tend to shed mass by α decay (and some by spontaneous fission). (stability line at Z ≈ 92.4 for A = 238)

Decay explorer

α decay

²³⁸U → ²³⁴Th + α

Conserved	Left	Right
Nucleon number A	238	238	✓
Charge Z (in e)	92	92	✓
Lepton number L	0	0	✓

α is a reported decay mode of U-238.

Conservation laws are necessary, not sufficient: the decay must also release energy (Q > 0), which is not computed here.

Half-life lab

Half-life

From the bundled reference.

Initial amount

Elapsed time

Elapsed: 2.238 × 10⁻¹⁰ half-lives
Fraction remaining N/N₀: 1 (100 %)
Nuclei remaining: 2.530 × 10²¹
Mass remaining (≈ A g/mol): 1 g
Decay constant λ: 4.916 × 10⁻¹⁸ s⁻¹
Activity now / initially: 12440 / 12440 Bq

Time until% remains:8.936 × 10⁹ y

N = N₀·2^(−t/T½) for a single nuclide with no ingrowth from parents. Mass uses A g/mol as the molar mass.

What this result is — and isn’t

User-built candidate. You chose this nuclide, decay mode or equation. Writing a balanced equation does not mean the process is observed.
Rule-based assessment. Conservation of nucleon number, charge and lepton number (balanced for the selected decay). Rule-of-thumb stability hints are not data.
Database-supported material. Half-life and decay modes come from a small hand-bundled table of ~70 well-known nuclides, rounded. Verify against NUBASE / ENSDF before quoting.
Calculated result. No Q-values, binding energies or branching ratios are computed; only the decay law is evaluated.

Symbol check: U · units of the decay lab convert with 1 y = 365.25 d.