Unoctennium, Uoe, is the temporary name for element 189. Some nuclides of this element are likely, but no mechanism is known by which they can form. Some very neutron-rich nuclear drops with Z = 189 may form during a neutron star merger, but they are likely to fission promptly, before they qualify as nuclei.
Nuclear properties[]
No predictions for half-life or decay modes are available for elements with Z > 175. It is possible to determine a boundary in the (Z,A) {or (Z,N)} plane outside of which no nuclides are possible, as detailed in The Final Element.
A nuclear drop containing 189 protons and more than 641 neutrons must decay by neutron emission with a half-life under 10-14 sec. A drop with 189 protons and fewer than 297 neutrons must decay by spontaneous fission with a half-life under 10-14 sec. Nuclear drops in the band from 830Uoe to 486Uoe are not required to decay either by neutron emission or by fission, so it is possible they will survive the 10-14 sec needed for them to become nuclides.
The boundary described above was arrived at by applying large factors of safety to quantities which have been predicted. By looking at which factors apply to a particular (Z,A) point, it is possible to make a qualitative guess how likely it is that (Z,A) is a nuclide. Details of this method are given in Nuclear Guesswork. What follows should not be considered predictions, only guesses as to what might be. Likelihood that a nuclide can exist are given in four categories: likely, unlikely, improbable, and not impossible.
Nuclear drops in the bands 830Uoe to 803Uoe and 718Uoe to 693Uoe are likely to decay by neutron emission but are stable against fission. Nuclides in these bands are unlikely. 692Uoe and drops in the band 802Uoe to 719Uoe are likely to decay by neutron emission and require a moderate amount of structural correction energy. Nuclides in these bands are improbable. Drops in the band 596Uoe to 590Uoe are unlikely to decay by neutron emission and are stable against fission. Nuclides in this band are likely. Drops in the bands 691Uoe to 597Uoe and 589Uoe to 553Uoe are unlikely to decay by neutron emission and require a moderate amount of structural correction energy. Nuclides in these bands are unlikely. Drops in the band 552Uoe to 486Uoe are unlikely to decay by neutron emission but require large structural correction. Nuclides in this band are improbable.
Occurence[]
Formation[]
596Uoe to 590Uoe are likely to be nuclides. They are too far from the neutron dripline to form directly during a neutron star merger, and cannot form via beta decay because beta-decay chains from nuclides with suitable A terminate in fission at lower Z.
It is implausible that neutron capture can form any Uoe isotope.
Persistence[]
If any Uoe forms, it will decay away within 1000 sec of the neutron star merger that produced it.
Atomic properties[]
The nuclear charge of Uoe is so great that stationary-state orbital theory cannot describe its electrons. In addition, both nuclear size and nuclear shape may affect its electron structure. If these effects are small, and if the assumptions made in Period 9 Elements are valid, Uoe will be a 9th period active metal.
References[]
References are given in the articles cited.
Elements 175 and Beyond | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
175-226 | 175 Usp |
176 Ush |
177 Uss |
178 Uso |
179 Use |
180 Uon |
181 Uou |
182 Uob |
183 Uot |
184 Uoq |
185 Uop |
186 Uoh |
187 Uos |
188 Uoo |
189 Uoe |
190 Uen |
191 Ueu |
192 Ueb |
193 Uet |
194 Ueq |
195 Uep |
196 Ueh |
197 Ues |
198 Ueo |
199 Uee |
200 Bnn |
201 Bnu |
202 Bnb |
203 Bnt |
204 Bnq |
205 Bnp |
206 Bnh |
207 Bns |
208 Bno |
209 Bne |
210 Bun |
211 Buu |
212 Bub |
213 But |
214 Buq |
215 Bup |
216 Buh |
217 Bus |
218 Buo |
219 Bue |
220 Bbn |
221 Bbu |
222 Bbb |
223 Bbt |
224 Bbq |
225 Bbp |
226 Bbh | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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227-278 | 227 Bbs |
228 Bbo |
229 Bbe |
230 Btn |
231 Btu |
232 Btb |
233 Btt |
234 Btq |
235 Bth |
236 Bts |
237 Bts |
238 Bto |
239 Bte |
240 Bqn |
241 Bqu |
242 Bqb |
243 Bqt |
244 Bqq |
245 Bqp |
246 Bqh |
247 Bqs |
248 Bqo |
249 Bqe |
250 Bpn |
251 Bpu |
252 Bpb |
253 Bpt |
254 Bpq |
255 Bpp |
256 Bph |
257 Bps |
258 Bpo |
259 Bpe |
260 Bhn |
261 Bhu |
262 Bhb |
263 Bht |
264 Bhq |
265 Bhp |
266 Bhh |
267 Bhs |
268 Bho |
269 Bhe |
270 Bsn |
271 Bsu |
272 Bsb |
273 Bst |
274 Bsq |
275 Bsp |
276 Bsh |
277 Bss |
278 Bso | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
279-324 | 279 Bse |
280 Bon |
281 Bou |
282 Bob |
283 Bot |
284 Boq |
285 Bop |
286 Boh |
287 Bos |
288 Boo |
289 Boe |
290 Ben |
291 Beu |
292 Beb |
293 Bet |
294 Beq |
295 Bep |
296 Beh |
297 Bes |
298 Beo |
299 Bee |
300 Tnn |
301 Tnu |
302 Tnb |
303 Tnt |
304 Tnq |
305 Tnp |
306 Tnh |
307 Tns |
308 Tno |
309 Tne |
310 Tun |
311 Tuu |
312 Tub |
313 Tut |
314 Tuq |
315 Tup |
316 Tuh |
317 Tus |
318 Tuo |
319 Tue |
320 Tbn |
321 Tbu |
322 Tbb |
323 Tbt |
324 Tbq |
325+ Tbp+ |
Likelihood of an Element's Existence | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Likely | Unlikely | Improbable | Not Impossible | Um. |
(05-28-20)