Six astatine isotopes, with mass numbers of 214 to 219, are present in nature as the products of various decay routes of heavier elements, but neither the most stable isotope of astatine ( with mass number 210 ) nor astatine-211 ( which is used in medicine ) is produced naturally.

It is placed as the heaviest member of group 9 ( or VIII ) in the periodic table but a sufficiently stable isotope is not known at this time which would allow chemical experiments to confirm its position as a heavier homologue to iridium, unlike its lighter neighbors.

Nickel-78's half-life was recently measured to be 110 milliseconds and is believed to be an important isotope involved in supernova nucleosynthesis of elements heavier than iron.

Because no isotope of technetium has a half-life longer than 4. 2 million years ( technetium-98 ), its detection in 1952 in red giants, which are billions of years old, helped bolster the theory that stars can produce heavier elements.

The primary decay mode of ytterbium isotopes lighter than the most abundant stable isotope, < sup > 174 </ sup > Yb, is electron capture, and the primary decay mode for those heavier than < sup > 174 </ sup > Yb is beta decay.

It is placed as the heaviest member of group 10, but no known isotope is sufficiently stable to allow chemical experiments to confirm its placing in that group as a heavier homologue to platinum.

However, recent advances in mass spectrometry ( i. e. multiple-collector inductively coupled plasma mass spectrometry ) now enable the measurement of isotope ratios in heavier stable elements, such as iron, copper, zinc, molybdenum, etc.

Primordial nucleosynthesis is believed by many scientists to have taken place just a few moments after the Big Bang and is believed to be responsible for the formation of a heavier isotope of hydrogen known as deuterium ( H-2 or D ), the helium isotopes He-3 and He-4, and the lithium isotopes Li-6 and Li-7.

Water molecules containing the heavier O-18 evaporate at a higher temperature than water molecules containing the normal Oxygen-16 isotope.

It is placed as the heaviest member of the group 11 ( IB ) elements, although a sufficiently stable isotope has not yet been produced in a sufficient amount that would confirm this position as a heavier homologue of gold.

It is placed as the heaviest member of group 16 ( VIA ) although a sufficiently stable isotope is not known at this time to allow chemical experiments to confirm its position as a heavier homologue to polonium.

It is placed as the heaviest member of group 15 ( VA ) although a sufficiently stable isotope is not known at this time that would allow chemical experiments to confirm its position as a heavier homologue to bismuth.

It reveals a general increasing stability trend for isotopes heavier than < sup > 301 </ sup > Uus, the isotope that has 184 neutrons, considered to be a magic number in physics that is thought to provide extra stability.

It is placed as the heaviest member of the group 13 ( IIIA ) elements although a sufficiently stable isotope is not known at this time that would allow chemical experiments to confirm its position as a heavier homologue to thallium.

A less moderated neutron energy spectrum does worsen the capture / fission ratio for < sup > 235 </ sup > U and especially < sup > 239 </ sup > Pu, meaning that more fissile nuclei fail to fission on neutron absorption and instead capture the neutron to become a heavier nonfissile isotope, wasting one or more neutrons and increasing accumulation of heavy transuranic actinides, some of which have long half-lives.

Similarly, ice cores on land are enriched in the heavier < sup > 18 </ sup > O relative to < sup > 16 </ sup > O during warmer climatic phases ( interglacials ) as more energy is available for the evaporation of the heavier < sup > 18 </ sup > O isotope.

< sup > 14 </ sup > N is by far the most abundant isotope of nitrogen, but DNA with the heavier ( but non-radioactive ) < sup > 15 </ sup > N isotope is also functional.

Some carboxylases, particularly RuBisCO, preferentially bind the lighter carbon stable isotope carbon-12 over the heavier carbon-13.

Denser water salinity also tends to contain the heavier isotope.

The rate of a reaction involving a C-H bond is typically 6 to 10 times faster than the corresponding C-D bond, whereas a < sup > 12 </ sup > C reaction is only ~ 1. 04 times faster than the corresponding < sup > 13 </ sup > C reaction ( even though, in both cases, the isotope is one atomic mass unit heavier ).

Based on the principle that molecules of a lighter isotope would pass through a porous barrier more readily than molecules of a heavier one, gaseous diffusion of uranium hexafluoride produced a gas increasingly rich in uranium-235 as the heavier uranium-238 was separated out in a system of cascades.

As this plutonium was intended for weapons purposes, the burn-up of the fuel would have been kept low to reduce production of the heavier plutonium isotopes (< sup > 240 </ sup > Pu, < sup > 241 </ sup > Pu etc.

Only < sup > 95 </ sup > Nb ( 35 days ) and < sup > 97 </ sup > Nb ( 72 minutes ) and heavier isotopes ( half-lives in seconds ) are fission products in significant quantity, as the other isotopes are shadowed by stable or very long-lived (< sup > 93 </ sup > Zr ) isotopes of the preceding element zirconium from production via beta decay of neutron-rich fission fragments.

Isotopes that are lighter than the stable < sup > 123 </ sup > Sb tend to decay by β < sup >+</ sup > decay, and those that are heavier tend to decay by β < sup >-</ sup > decay, with some exceptions.

Curium is used in production of heavier actinides and of the < sup > 238 </ sup > Pu radionuclide for power sources in artificial pacemakers.

The least stable is < sup > 138 </ sup > Dy with a half-life of 200 ms. Isotopes that are lighter than the stable isotopes tend to decay primarily by β < sup >+</ sup > decay, while those that are heavier tend to decay by β < sup >−</ sup > decay, with some exceptions.

The primary decay mode for isotopes lighter than < sup > 153 </ sup > Eu is electron capture, and the primary mode for heavier isotopes is beta minus decay.

Additionally, they were able to plasmolyze the bacteriophages so that they went into osmotic shock, which effectively created a solution containing most of the < sup > 32 </ sup > P and a heavier solution containing structures called “ ghosts ” which contained the < sup > 35 </ sup > S and the protein coat of the virus.

Isotopes heavier than < sup > 62 </ sup > Ni cannot be formed by nuclear fusion without losing energy.

The intensity of Thomson scattering declines as 1 / m < sup > 2 </ sup > with the mass m of the charged particle that is scattering the radiation ; hence, the atomic nuclei, which are thousands of times heavier than an electron, contribute negligibly to the scattered X-rays.

The heavier homologues readily form the volatile, reactive hexahalides MX < sub > 6 </ sub > ( X = Cl, F ).

) For comparison, the Sun has an abundance of elements heavier than helium of about Z < sub > Sol </ sub > = 0. 0172 ± 0. 002.

Bluefish commonly range in size from seven-inch ( 18-cm ) " snappers " to much larger, sometimes weighing as much as 40 pounds ( 18 kg ), though fish heavier than twenty pounds ( 9 kg ) are exceptional.

During colder periods of the Earth's history ( glacials ) such as during the ice ages, < sup > 16 </ sup > O is preferentially evaporated from the colder oceans, leaving the slightly heavier and more sluggish < sup > 18 </ sup > O behind.

The Nuffield Organisation responded with 18 separate designs ( AT1 through AT18 ) drafted between May 1943 and February 1944, each design larger and heavier than the last.

I Zwicky 18 may still be creating Population III stars — spectroscopy shows that its stars are composed almost entirely of hydrogen and helium, with heavier elements almost completely absent.

The breed is often described as about 35 pounds ( 16 kg ) and 18 to 20 inches ( 0. 45 to 0. 5 m ) at the shoulder, but the average is somewhat heavier, around 45 pounds ( 20 kg ) with some males reaching or slightly exceeding 60 pounds ( 27 kg ) and up to 22 inches ( 0. 55 m ).

In each case the American ships were substantially larger than the British vessels and had a heavier broadside ( the Americans had a main battery of 24 pounder long guns compared with the smaller 18 pounders mounted on the British ships ).

Acrylic is more dense than most woods ( specific gravity of acrylic is 1. 18 g / cm3 while that of lignum vitae, probably the heaviest of woods, is approximately 1. 23g / cm3 ) which makes the guitar heavier.

Oxygen 18 ( < sup > 18 </ sup > O ) occurs in approximately one oxygen atom in every five hundred and is a bit heavier than oxygen 16, as it has two extra neutrons.

In the spring of 1935 this vehicle was refitted with heavier armour and a standard APX turret, attached by the Atelier de Rueil between 18 and 25 April.

In this instance, isotopically lighter water molecules ( i. e., those with < sup > 16 </ sup > O ) will evaporate slightly more easily than will the isotopically heavier water molecules with < sup > 18 </ sup > O.