Naturally occurring tritium is extremely rare on Earth, where trace amounts are formed by the interaction of the atmosphere with cosmic rays. Promethium is a chemical element with atomic number 61 which means there are 61 protons and 61 electrons in the atomic structure. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. There are only certain combinations of neutrons and protons, which forms stable nuclei. The chemical symbol for Erbium is Er. The difference is a measure of the nuclear binding energy which holds the nucleus together. The chemical symbol for Argon is Ar. In fact, it's actually possible to have an atom consisting of only a proton (ionized hydrogen). Nickel is a chemical element with atomic number 28 which means there are 28 protons and 28 electrons in the atomic structure. Consumption of heavy water does not pose a health threat to humans. Silicon is a hard and brittle crystalline solid with a blue-grey metallic lustre, it is a tetravalent metalloid and semiconductor. Bismuth is a brittle metal with a silvery white color when freshly produced, but surface oxidation can give it a pink tinge. For example, actinides with odd neutron number are usually fissile (fissionable with slow neutrons) while actinides with even neutron number are usually not fissile (but are fissionable with fast neutrons). The chemical symbol for Thulium is Tm. Boron is a chemical element with atomic number 5 which means there are 5 protons and 5 electrons in the atomic structure. The name of the gas is formed from two Greek words, meaning water and forming, so this is the element which creates water. The chemical symbol for Rhenium is Re. The two remaining protons were detected by the “RIKEN telescope”, a device composed of several layers of sensors, positioned behind the target of the RI Beam cyclotron. The chemical symbol for Technetium is Tc. Europium is one of the least abundant elements in the universe. Hydrogen atoms are so reactive that they combine with almost all elements. To determine the stability of an isotope you can use the ratio neutron/proton (N/Z). Hydrogen is a chemical element with atomic number 1 which means there are 1 protons and 1 electrons in the atomic structure. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the noble gas group in the periodic table. Gold is a transition metal and a group 11 element. This equilibrium also known as “samarium 149 reservoir”, since all of this promethium must undergo a decay to samarium. Units of measure have been defined for mass and energy on the atomic scale to make measurements more convenient to express. Tin is a chemical element with atomic number 50 which means there are 50 protons and 50 electrons in the atomic structure. Chlorine is a yellow-green gas at room temperature. The chemical symbol for Molybdenum is Mo. Naturally occurring potassium is composed of three isotopes, of which 40K is radioactive. Neon is a chemical element with atomic number 10 which means there are 10 protons and 10 electrons in the atomic structure. It is plenty in nature with an abundance of 99.98%. Hydrogen generally combines with other atoms in compounds and are usually found in H2( diatomic hydrogen gas). Titanium is resistant to corrosion in sea water, aqua regia, and chlorine. Neptunium metal is silvery and tarnishes when exposed to air. Lithium is a chemical element with atomic number 3 which means there are 3 protons and 3 electrons in the atomic structure. The chemical symbol for Francium is Fr. These have similar chemical properties, but palladium has the lowest melting point and is the least dense of them. Molybdenum is a chemical element with atomic number 42 which means there are 42 protons and 42 electrons in the atomic structure. Properties of atomic nuclei (atomic mass, nuclear cross-sections) are determined by the number of protons and number of neutrons (neutron number). Rhodium is a rare, silvery-white, hard, corrosion resistant and chemically inert transition metal. Therefore, we cannot determine the neutron number of uranium, for example. Atomic Mass Number – Does it conserve in a nuclear reaction? Deuterium occurs in trace amounts naturally as deuterium gas, written 2H2 or D2, but is most commonly found in the universe bonded with a protium 1H atom, forming a gas called hydrogen deuteride (HD or 1H2H). Europium is a moderately hard, silvery metal which readily oxidizes in air and water. Oxygen is a chemical element with atomic number 8 which means there are 8 protons and 8 electrons in the atomic structure. In nuclear industry boron is commonly used as a neutron absorber due to the high neutron cross-section of isotope 10B. The chemical symbol for Promethium is Pm. Natural boron consists primarily of two stable isotopes, 11B (80.1%) and 10B (19.9%). Titanium is a lustrous transition metal with a silver color, low density, and high strength. On the other hand, nuclei with an odd number of protons and neutrons are mostly unstable. Radon is a radioactive, colorless, odorless, tasteless noble gas. The chemical symbol for Holmium is Ho. Titanium condenser tubes are usually the best technical choice, however titanium is very expensive material. It is obtained chiefly from the mineral cassiterite, which contains tin dioxide. For other isotopes, the isotopic mass usually differs and is usually within 0.1 u of the mass number. Polonium is a rare and highly radioactive metal with no stable isotopes, polonium is chemically similar to selenium and tellurium, though its metallic character resembles that of its horizontal neighbors in the periodic table: thallium, lead, and bismuth. The chemical symbol for Rhodium is Rh. The chemical symbol for Gallium is Ga. Gallium has similarities to the other metals of the group, aluminium, indium, and thallium. It has been synthesized in the laboratory by bombarding tritium with fast-moving deuterium nuclei. Radium is a chemical element with atomic number 88 which means there are 88 protons and 88 electrons in the atomic structure. There are two reasons for the difference between mass number and isotopic mass, known as the mass defect: Note that, it was found the rest mass of an atomic nucleus is measurably smaller than the sum of the rest masses of its constituent protons, neutrons and electrons. Only about 5×10−8% of all matter in the universe is europium. Rubidium is a chemical element with atomic number 37 which means there are 37 protons and 37 electrons in the atomic structure. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype. Actinium gave the name to the actinide series, a group of 15 similar elements between actinium and lawrencium in the periodic table. CC BY-SA 3.0. http://en.wikipedia.org/wiki/Hydrogen_isotopes Arsenic is a chemical element with atomic number 33 which means there are 33 protons and 33 electrons in the atomic structure. If there are too many or too few neutrons for a given number of protons, the resulting nucleus is not stable and it undergoes radioactive decay. Unstable isotopes decay through various radioactive decay pathways, most commonly alpha decay, beta decay, gamma decay or electron capture.