1. Heavy elements
By: stephany flores
Website:
https://www.facebook.com/pages/Step
hany-fg/141859819322413?ref=hl

2. what is a heavy element?
• A heavy element is an element with an atomic
number greater than 92. The first heavy
element is neptunium (Np), which has an
atomic number of 93. Some heavy elements
are produced in reactors, and some are
produced artificially in cyclotron experiments.

3. What is a superheavy element?
• The definition of superheavy elements (SHE)
varies among different groups of people. We use
the term term SHE to refer to those elements
with an atomic number greater than or equal to
112. The first superheavy element is element
113, which has been recently discovered by a
collaboration of scientists from the Lawrence
Livermore National Laboratory and the Joint
Institute of Nuclear Research in Russia. Like some
of the heavy elements, superheavy elements are
produced artificially in cyclotron experiments.

4. What is an atomic number?
• The atomic number refers to the number of
protons in an element’s nucleus. Each element
has a unique atomic number and is known by
that number until it receives an official name.
For example, the two new superheavy
elements 113 and 115 have 113 and 115
protons, respectively, in their nuclei.

5. What are isotopes?
• Elements are defined by their atomic numbers
or number of protons in the nucleus.
Elements, however, have more than one
isotope. An isotope contains varying numbers
of neutrons in the nucleus. Gold, for
example, has one stable isotope often
denoted as

6. What are isotopes?
• . It has an atomic number of 79 (meaning 79
protons in the nucleus) and a mass number of
197, or the total number of neutrons and
protons in the nucleus. Thus, there are 197 –
79 = 118 neutrons in this isotope.
However, more than 30 isotopes of gold are
known. Each isotope has its own decay
characteristics and half-life.

7. What are isotopes?
• For example, , an isotope with one more
neutron (119) that the stable isotope , has a
half-life of 2.7 days and decays by beta-decay.
A very different gold isotope, , has a half-life
of 5 ms and decays by alpha-decay.

8. How are new elements discovered?
• Several experimental techniques have been
used to make new chemical elements. Some
of these include heavy ion transfer
reactions, cold or hot fusion evaporation
reactions, neutron capture reactions, light-ion
charged particle induced reactions, and even
nuclear explosions. These techniques each
have advantages and disadvantages making
them suitable for studying nuclei in certain
regions.

9. How are new elements discovered?
• The types of nuclear reactions that have been
successfully used to produce new elements in the
last decade are cold fusion reactions and hot
fusion reactions. Cold fusion reactions use beam
and target nuclei that are closer to each other in
mass in order to produce a compound nucleus
(the complete fusion of one target nucleus with
one beam nucleus) with generally lower
excitation energy that typically requires
evaporation of one or no neutrons..

10. How are new elements discovered?
• This generates fewer neutron-rich isotopes of
an element that have higher survival
probabilities with respect to fission, but have
lower fusion probabilities. An example of this
type of reaction is 70Zn + 208Pb → 277112 + 1n
with a cross-section of ~1 picobarn

11. How are new elements discovered?
• Because the 112 isotope ultimately decays by a
emission to known nuclei [namely isotopes of
elements 102 (No) and 104 (Rf)], identification of
this element is straightforward. Hot fusion
reactions use more asymmetric beam and target
nuclei, produce a compound nucleus with
generally higher excitation energy that typically
requires evaporation of three to five
neutrons, generate more neutron-rich isotopes of
an element, have lower survival probabilities with
respect to fission, but have higher fusion
probabilities.

12. How are new elements discovered?
• An example of this type of reaction is 48Ca
+ 244Pu → 288114 + 4n with a cross-section of
~1 pb. Because of the neutron-richness of this
isotope of element 114, it never subsequently
decays to any known isotope, and thus its
identification is more problematic. Cold fusion
reactions have been successful in producing
elements 104—112 and hot fusion reactions
have recently provided evidence for elements
113—116 and 118.

13. What is a cyclotron?
• A cyclotron is a particle accelerator that
boosts ions to very high velocities through a
series of small kicks as the ions travel in a
circular motion (or spiral). The cyclotron was
invented at the University of
California, Berkeley, by Ernest O.
Lawrence, the namesake of the Lawrence
Livermore National Laboratory.

14. What are some properties of
artificially made isotopes?
• Isotopes of various elements that are created
artificially in accelerator experiments are
unstable and radioactive. Once produced, these
new isotopes begin to decay; that is, change into
another isotope. The time required for half of an
isotope’s atoms to decay is called the isotope’s
half-life. As the atomic number of each new
heavy element increases, the half-life typically
decreases, meaning that new elements tend to
decay more quickly.

15. What are some properties of
artificially made isotopes?
• However, physicists in the 1960s predicted
that this trend toward shorter half-lives would
change around element 114. They thought
that some elements around element 114
would have longer half-lives, forming an
“island of stability” in the midst of a “sea” of
highly unstable elements.

16. What is the “island of stability”?
• The "island of stability" refers to a predicted
region of superheavy elements on the chart of
nuclides with half-lives that are longer by
several orders of magnitude than the half-lives
of other superheavy elements. Half-lives for
elements in the island of stability may range
from seconds to minutes, while half-lives for
other superheavy elements may be measured
in micro- or nanoseconds.

17. What is the “island of stability”?
• The existence of the island of stability was
shown in 1998 with the discovery of the
superheavy element 114. The island of
stability is a specific subset of the superheavy
elements, which is characterized by nuclei that
have a spherical shape.

18. What is the “sea of instability”?
• The "sea of instability" refers to a region of
elements on the periodic table that are highly
unstable. These elements have extremely
short half-lives that may be measured in
micro- or nanoseconds. (A nanosecond is the
time it takes for light to travel one foot.) This
region of unstable elements surrounds the
island of stability.

19. Why is discovering new superheavy
elements important?
• Discovering new superheavy elements proves long-
held nuclear theories regarding the existence of the
“island of stability” and the ultimate limits of the
periodic table of the elements. These discoveries also
help scientists to better understand how nuclei are
held together and how they resist the fission process.
The skills that are acquired by conducting these heavy-
element experiments can then be applied to solving
national needs like stockpile stewardship and
homeland security. For example, an improved
understanding of the fission process will enable
scientists to enhance the safety and reliability of the
nation’s nuclear stockpile and nuclear reactors.

20. How can superheavy elements be
used?
• Like most scientific discoveries, researchers do
not yet know the immediate practical
applications of the discovery of elements 113 and
115. Previously discovered heavy elements are
used in smoke detectors (americium), neutron
radiography and neutron interrogation (curium
and californium), and nuclear weapons
(plutonium). Scientists expect that practical
applications of elements 113 and 115 also exist
and will be discovered in the future.

21. How long did it take to discover elements
113, 114, 115, 116, and 118?
• Elements 113 and 115—The experiment began
on July 14, 2003, and ended on August 10, 2003.
In that time, four atoms of element 115 were
produced that decayed after a given
time, thereby producing element 113, which also
decayed and so on. However, years of successful
experiments, previous to the 115 and 113
discovery, were needed to show that the
experiment could be successful. More than a year
was then spent to clean the target material, ship
it to Russia, make the target, and run the
experiment.

22. • Element 114—The first element 114 experiment
lasted about one year, and two atoms were
discovered during that time.
• Element 116—The element 116 experiment also
lasted about one year, and three atoms were
discovered during that time.
• Element 118—Element 118 was produced during
two separate experiments, each one lasting for
several months. A total of three atoms were
discovered in both experiements combined.
How long did it take to discover
elements 113, 114, 115, 116, and
118?