Tritium, atomic symbol

The italicized symbols d- (for deuterium) and t- (for tritium) are placed after the formula and connected to it by a hyphen. The number of deuterium or tritium atoms is indicated by a subscript to the symbol. 

Hydrogen The first chemical element in the periodic table. It has the atomic symbol H, atomic number 1, and atomic weight 1. It exists, under normal conditions, as a colorless, odorless, tasteless, diatomic gas. Hydrogen ions are protons. Besides the common HI isotope, hydrogen exists as the stable isotope deuterium and the unstable, radioactive isotope tritium. [NIH]... 

Note that of all the isotopes of all the elements, only those of hydrogen, and H, also have specific atomic symbols, D and T, with associated names deuterium and tritium. 

Tritium is the heavy isotope of hydrogen (section 5.2). Its symbol is 3H, or T. Tritium atoms are unstable and disintegrate radioactively, forming stable 3He atoms. The radioactive decay is accompanied by the emission of [1 particles, measurable in specific laboratories ... 

In equation (9), as in the following equations, the symbol H printed in heavy type indicates a labeled species containing an unspecified number of tritium atoms. 

Usually all the isotopes of an element share the same name and atomic symbol. The exception is hydrogen. Isotope fH is called deuterium (symbol D), and fH is tritium (T). 

Examples of isotopes are abundant. The major form of hydrogen is represented as H (or H-1), with one proton H, known as the isotope deuterium or heavy hydrogen, consists of one proton and one neutron (thus an amu of 2) and is the isotope of hydrogen called tritium with an amu of 3. Carbon-12 ( C or C-12) is the most abundant form of carbon, though carbon has several isotopes. One is the C isotope, a radioactive isotope of carbon that is used as a tracer and to determine dates of organic artifacts. Uranium-238 is the radioactive isotope (Note The atomic number is placed as a subscript prefix to the element s symbol—for example, —and the atomic mass number can be written either as a dash and number fol-... 

A hydrogen isotope with a nucleus consisting of one proton and two neutrons (the nucleus is referred to as the triton). Tritium, a radioisotope symbolized by iH or T, decays by negative beta emission (0.01860 MeV) with a half-life of 12.32 years. The atomic weight of tritium is 3.01605 amu. It is frequently used in metabolic and kinetic experiments. The following decay data indicate the time followed by the fraction of original amount at the specified time 0, 1.000 1 month, 0.995 2, 0.991 3,... 

Symbol H atomic number 1 atomic weight 1.0079 the lightest of all the chemical elements the first element in the Periodic Table Group lA (group 1) nonmetallic gaseous element occurs as H2, a diatomic molecule electron configuration Ish valences -i-l and-1 three isotopes H-1 or protium (99.9844%), H-2 or deuterium (0.0156%), H-3 or tritium (radioactive, ty, =12.4 yr., in traces... 

A given isotope is represented by showing its element symbol with mass number as a left superscript and atomic number as a left subscript. Thus, protium is represented as jH, deuterium as jH, and tritium as fH. Similarly, the two naturally... 

Hydrogen-2 is called deuterium and is often represented by the symbol D. Hydrogen-3 is known as tritium and is often represented by the symbol T. Nuclear reactions between very light atoms similar to the reaction above are the energy source behind the sun and the hydrogen bomb. 

A nuclear species (nuclide) is characterized by its atomic number Z (that is, the nuclear charge in units of e, or the number of protons in the nucleus) and its mass number A (the sum of the number of protons plus the number of neutrons in the nucleus). We denote an atom that contains such a nuclide with the symbol zX, where X is the chemical symbol for the element. The atomic number Z is sometimes omitted because it is implied by the chemical symbol for the element. Thus, JH (or H) is a hydrogen atom and (or C) is a carbon atom with a nucleus that contains six protons and six neutrons. Isotopes are nuclides of the same chemical species (that is, they have the same Z), but with different mass numbers A, and therefore different numbers of neutrons in the nucleus. The nuclear species of hydrogen, deuterium, and tritium, represented by JH, jH, and jH, respectively, are all members of the family of isotopes that belong to the element hydrogen. 

Hydrogen is the first element, and so has an atomic number of one. Its electronic configuration is Is1. There are three isotopes protium, deuterium and tritium, which may be represented by the symbols 1H, 2H or 3H, or alternatively, H, D or T. The cation of hydrogen is a bare proton, H+ (Is0) while the anion of hydrogen is called a hydride anion, H (Is ) (or more strictly, a protiide anion). 

The mass number for normal hydrogen atoms is 1 for deuterium, 2 and for tritium, 3. The composition of a nucleus is indicated by its nuclide symbol. This consists of the symbol for the element (E), with the atomic number (Z) written as a subscript at the lower left and the mass number (A) as a superscript at the upper left, By this system, the three isotopes of hydrogen are designated as H, H, and ]H. 

The sum of the numbers of protons and neutrons in the nucleus of an atom is called the atom s mass number. Isotopes have the same atomic number but different mass numbers. To distinguish one isotope from another, the symbol for the element is often followed by the mass number of the isotope. For example, the mass number of the most common isotope of hydrogen, with one proton and no neutrons, is 1, so its symbol is H-1. The other natural isotope of hydrogen, with one proton and one neutron, has a mass number of 2 and a symbol of H-2. Tritium, H-3, the radioactive form of hydrogen, has a mass number of 3. All of these isotopes of hydrogen have an atomic number of 1. 

Another isotope of hydrogen, with an atomic weight 3 was reported in 1935 as present in natural waters. It occurs only ir very minute quantities to the tune of 1 part in io17 parts of water to this the name tritium was given, with symbol T. It is a shortlived element, with a half life of about 30 yearsf. 

As we have seen in Giapter 1, an elemrat may be conqx>sed of atoms that, while having the same number of protons in the nuclei, have different mass numbers and, therefore, different numbers of neutrons. Neon, for exanq>le, has an atomic number of 10, which means that the number of protons in the nuclei of all neon atoms is 10 however, 90% of the neon atoms in nature have 10 neutrons present in their nuclei while 10% of die atoms have 12 neutrons. Such atoms of constant Z but differrat A are called isotopes. The heavy hydrogen isotopes and are used so oftm in nuclear science that they have been given special names and symbols, deuterium (D) and tritium (T), respectively. 

Special name Chemical symbol Atomic number Z Hydrt en H 1 Deuterium HorD 1 Tritium 5r orT 1 Helium 4 He 2 Helium 3 5He 2 ... 

There are two methods for specifying isotopes. In the first, the mass number appears with a hyphen after the name of the element. Tritium, for example, is written as hydrogen-3. We call this method hyphen notation. The uranium isotope with mass number 235, commonly used as fuel for nuclear power plants, is known as uranium-235. The second method shows the composition of a nucleus using the isotope s nuclear symbol. So uranium-235 is shown as u. The superscript indicates the mass number (protons -I- neutrons). The subscript indicates the atomic number (number of protons). The number of neutrons is found by subtracting the atomic number from the mass number. 

The first isotcpe, with 235 — 92 = 143 neutrons in its nucleus, is used in nuclear reactors and atomic bombs, whereas the second isotr, with 146 neutrons, lacks the fffoperties necessary for these applications. With the exception of hydrogen, which has different names for each of its isotopes, the isotopes of other elements are identified by their mass numbers. The two isotopes of uratrium are called uranium-235 (pronounced Tiianium two thirty-five ) and uranium-238 (jx onounced uranium two thirty-eight ). Because the subscripted atomic number can be determined from the elemental symbol, it may be omitted from these representations without the loss of any inframatirai. The symbols and are sufficient to spediy the isotopes tritium and uranium-235, respectively. 

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