Hyphen notation

Write the hyphen notation for the element that contains 15 electrons and 15 neutrons. 

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. 

Write the nuclear symbol and hyphen notation for each of the following isotopes ... 

Use the periodic table and the information that follows to write the hyphen notation for each isotope described. 

The basic characters from which the notations are constructed comprise the upper-case letters A-Z of the alphabet, the numerals zero (symbolized 0) to nine (0-9), three punctuation marks hyphen (-), ampersand ( ) and oblique (/) and a blank space. Many of the normal atomic symbols such as B, F, P, 1, etc., are also employed unchanged but frequently occurring important elements and groups are assigned a single letter notation (e.g. chlorine sG ... 

There are two competing and equivalent nomenclature systems encountered in the chemical literature. The description of data in terms of ways is derived from the statistical literature. Here a way is constituted by each independent, nontrivial factor that is manipulated with the data collection system. To continue with the example of excitation-emission matrix fluorescence spectra, the three-way data is constructed by manipulating the excitation-way, emission-way, and the sample-way for multiple samples. Implicit in this definition is a fully blocked experimental design where the collected data forms a cube with no missing values. Equivalently, hyphenated data is often referred to in terms of orders as derived from the mathematical literature. In tensor notation, a scalar is a zeroth-order tensor, a vector is first order, a matrix is second order, a cube is third order, etc. Hence, the collection of excitation-emission data discussed previously would form a third-order tensor. However, it should be mentioned that the way-based and order-based nomenclature are not directly interchangeable. By convention, order notation is based on the structure of the data collected from each sample. Analysis of collected excitation-emission fluorescence, forming a second-order tensor of data per sample, is referred to as second-order analysis, as compared with the three-way analysis just described. In this chapter, the way-based notation will be arbitrarily adopted to be consistent with previous work. 

There are two standard methods of identifying isotopes. One method is to write the mass number with a hyphen after the name of an element. For example, the helium isotope shown on the left in Figure 14 is written helium-3, while the isotope shown on the right is written as helium-4. The second method shows the composition of a nucleus as the isotope s nuclear symbol. Using this method, the notations for the two helium isotopes shown in Figure 14 are written below. 

Another approach for representing 2D chemical structures is the linear notation. Linear notations are strings that represent the 2D structure as a more or less complex set of characters and symbols. Characters represent the atoms in a linear manner, whereas symbols are nsed to describe information about the connectivity [3]. The most commonly nsed notations are the Wiswesser line notation (WLN) and the simpUfled molecnlar inpnt line entry specihcation (SMILES) [2]. The WLN, invented by William J. Wiswesser in the 1949, was the hrst line notation capable of precisely describing complex molecnles [4]. It consists of a series of uppercase characters (A-Z), numerals (0-9), the ampersand ( ), the hyphen (-), the oblique stroke (/), and a blank space. 

Wiswesser Line Notation is the first line notation capable of precisely describing complex molecules consisting of a series of uppercase characters, numerals, and symbols (i.e., ampersand, hyphen, the oblique stroke, and a blank space). 

Figure 4.8. Simultaneous components notation of the PARAFAC model of the hyphenated data.

The complete amino acid sequence of a P. is shown by linking the 3-letter amino acid symbols by hyphens. If only part of a sequence is shown, the terminal symbols must also carry a second hyphen, e.g. -Ala-Ile-Val-Lys-. If part of a sequence is unknown the symbols are enclosed in parentheses and separated by commas, e.g. Ser-Phe-Gly-(Tyr, Asn, Val)-Pro-Ala. Using the one-letter notation (see Amino acids), this peptide would be represented as SFG(Y,B,V)PA, where the absence of punctuation between letters indicates a known sequence. 

Conjugated chromophores are denoted by the notation of componental unit chromophores joined by a hyphen. 

A second common notation for isotopes is the chemical symbol (or chemical name) followed by a hyphen and the mass number of the isotope. 

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