November in Physical Review Letters. It took about
a month just to find one atom of each element.
If researchers could coax these fleeting elements
to live longer, studying their properties might be
easier. Scientists have caught enticing visions of
increasing life spans lying just out of reach — the
fabled island of stability (SN: 6/5/10, p. 26). Scientists hope that the isotopes on that island, which
would be packed with lots of neutrons, may live
long enough that their chemistry can be studied
When the idea of an island of stability was proposed in the 1960s, scientists had suggested that
the isotopes on its shores might live millions of
years. Advances in theoretical physics have since
knocked that time frame down, Nazarewicz says.
Instead, nuclear physicists now expect the island’s
inhabitants to stick around for minutes, hours or
maybe even a day — a pleasant eternity for superheavy elements.
To reach the island of stability, scientists
must create new isotopes of known elements.
Researchers already know which direction they
need to row: They must cram more neutrons into
the nuclei of the superheavy elements that have
with protons. Oganesson may have a “bubble”
in its nucleus, with fewer protons in its center
than at its edges (SN: 11/26/16, p. 11). Still more
extreme nuclei may be doughnut-shaped,
Even the most basic properties of these ele-
ments, such as their mass, need to be measured.
While scientists had estimated the mass of the
various isotopes of the latest new elements using
indirect measurements, the arguments support-
ing those mass estimates weren’t airtight, says
Jacklyn Gates of Lawrence Berkeley National
Laboratory in California. “They hinge on physics
not throwing you a curveball.”
So Gates and colleagues directly measured the
masses of isotopes of nihonium and moscovium
using an accelerator at Lawrence Berkeley. An
apparatus called FIONA helped researchers mea-
sure the masses, thanks to electromagnetic fields
that steered an ion of each element onto a detec-
tor. The location where each ion hit indicated how
massive it was.
The nihonium isotope the researchers detected
had a mass number of 284, meaning its nucleus
had a combined total of 284 protons and neutrons.
Moscovium had a mass number of 288. Those
masses were as predicted, the scientists reported in
158 174 150 159 175 151 160 176 152 168 161 177 153 169 162 178 154 170 163 179 155 171 164 180 156 172 165 181 157 173 166 182 167 183 184 185 186
Long life Each row below is an element, and each column
a different isotope. Atoms are expected to be more
stable on the island of stability (predicted location
shown). As isotopes of elements (gray squares)
approach the island, they tend to live
longer, as more neutrons fill the
nucleus. Flerovium’s half-life,
for example, increases from
0.003 to two seconds.
SOURCES: S. HOFMANN
ET AL/PURE AND APPLIED
CHEMIS TR Y 2018;