Tc
Transition metal
Technetium
Z 43A 98mass 98
Slow-motion stage
Technetium-99m
proton
neutron
photon (γ) — no visible colour
Parent nucleus · 99 nucleons
43 protons (coral) and 56 neutrons (blue) are packed together and held by the strong force.
A real decay takes about 10⁻²¹ s. At ⅓× this stage stretches it across eleven seconds.
Choose a reaction
Reaction
9943Tc9943Tc+γ
An excited nucleus drops to a lower energy state and releases a photon.
Z
4343
no change
A
9999
no change
n⁰
5656
no change
Energy released
0.141MeV
Photon0.141 MeV
Mass convertedE = Δm c²0.00015 u
In joules2.25 × 10-14 J
Compared with a bonda C–C bond is 3.6 eV≈ 39,028 ×
Half-life of Technetium-99m
6.01 hours
The most used medical tracer: same nucleus, just less energy.
Photon energy & colour
Nuclear energy levels
this photon8.82 pm
0.1 pm1 pm10 pm100 pm
atomic emission lines380–780 nm
Hα 656 nmNa D 589 nmHβ 486 nmHg 436 nm
energy
140.5 keV
wavelength
8.82 pm
frequency
34.0 EHz
visible
no — too energetic
A 141 keV nuclear transition is about 74,361× the energy of hydrogen's red Hα line (656 nm), so its photon sits far beyond the violet end of the spectrum and carries no visible colour. It is drawn in deep violet only because that is the closest wavelength light can show.
The particle
- Charge
- 0
- Mass
- 0 (a photon)
- Speed
- The speed of light
- Ionising power
- Low
- Stopped by
- Centimetres of lead or a metre of concrete