Isotopic chlorine

The presence of a chlorine or bromine atom results in an intense (M + 2) peak due to the presence of either two chlorine isotopes (chlorine-35 and chlorine-37) or two bromine isotopes (bromine-79 and bromine-81). In the case of chlorine, the (M + 2) peak is about one-third the intensity of the M ... 

In other words, chlorine has a mass of 35.2 relative to hydrogen. This number is slightly different from the number that appears under chlorine in the periodic table. It was decided in the mid-20th century that, by convention, all masses listed in the periodic table would be relative to the carbon-12 isotope. Chlorine, therefore, has a mass of35.453 relative to the carbon-12 isotope. 

Halogenated compounds are particularly easy to identify b their mass spectra because both chlorine and bromine occur naturally as mixtures of two abundant Isotopes. Chlorine occurs as Cl (75.8 Mi) and - Cl (24.2%) bromine occurs as Br (50.7%) and Br (49.3%). At what masses do the molecular ions occur foi the following formulas What are the relative percentages of each molecular ion ... 

Most of the elements found in organic compounds, such as carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus, fluorine, and iodine, have one major isotope. Chlorine and bromine, on the other hand, have two, giving characteristic patterns to the mass spectra of their compounds. 

Chlorine has two stable isotopes, chlorine-35 and chlorine-37. The atomic number of chlorine is 17. Calculate the numbers of protons, electrons, and neutrons each isotope has. 

Most elements exist in nature in two or more isotopic forms. Chlorine, Cl, is a typical example. All samples of chlorine obtained from nature are composed of the same nonchanging mixture of two isotopes, chlorine-35 (Cl-35) and chlorine-37 (Cl-37). The 35 and 37 are the mass numbers of the two isotopes. Of course, both isotopes have the same atomic number, 17. 

Inspection of the periodic table reveals that the mass number of chlorine is actually 35.45 amu, not 35.00 amu. The existence of isotopes accounts for this difference. A natural sample of chlorine is composed principally of two isotopes, chlorine-35 and chlorine-37, in approximately a 3 1 ratio, and the tabulated mass is the weighted average of the two isotopes. In our calculation the chlorine atom referred to was the isotope that has a mass number of 35 amu. 

You must be careful when studying molecules containing chlorine or bromine atoms, since these elements have two commonly occurring isotopes. Chlorine has isotopes of 35 (relative abundance = 75.77%) and 37 (relative abundance = 24.23%) bromine has isotopes of 79 (relative abundance = 50.5%) and 81 (relative abundance = 49.5%). When these elements are present, take special care not to confuse the molecular ion peak with a peak corresponding to the molecular ion with a heavier halogen isotope present. 

Most elements occur naturally as a mixture of isotopes, differing from one another by the number of neutrons present in the nucleus. Natural carbon comprises a mixture of mainly and (98.9 and 1.1% respectively) with a trace of the radioactive isotope Chlorine has isotopes Cl (75.77%) and Cl (24.23%). Thus any mass spectrum will demonstrate a number of molecular ions due to the isotopomers present. Most data systems have programs which allow the input of a molecular formula which generates a theoretical isotopic distribution. This can then be compared with the actual spectrum obtained (Fig. 5.16). It may be necessary to add or subtract a proton from the inputted formula, hydrogen contains 0.015% deuterium. 

Each element has an atomic weight, a measure of the number of protons (the atomic number) and neutrons that make up its nucleus. Average atomic weights are used when an element exists naturally as different isotopes (elements with differing numbers of neutrons in the nucleus). For example, chlorine (atomic number 17) has two stable isotopes chlorine-35 and chlorine-37 which occur naturally in a 75.4 24.6% ratio. Thus, the average atomic weight is 35.5 ... 

Chemical modification of poly(vinyl chloride) (PVQ provided an important feature in a recent symposium devoted to this polymer. Contributions included the effects of tacticity on ionic dehydrochlorination and chlorination of PVC, and chemical methods, such as isotopic chlorine exchange, for the determination of labile chlorine. ... 

Carbon has two naturally occurring isotopes carbon-12 (mass = 12.00 amu) and carbon-13 (mass = 13.00 amu). Chlorine also has two naturally occurring isotopes chlorine-35 (mass = 34.97 amu) and chlorine-37 (mass = 36.97 amu). How many CCI4 molecules of different masses can exist Determine the mass (in amu) of each of them. 

A detector counts the numbers of each of the different ions that impact upon it, giving a measure of the percentage abundance of each isotope. The counter functions by releasing an electron for every ion it detects this signal is then amplified. A mass spectrum for chlorine atoms is shown in Figure 2.24. The two peaks are due to detection of and ions. The mass spectrum shows that chlorine is composed of two isotopes chlorine-35 and chlorine-37 in a 3 1 or 75% 25% ratio by abundance. 

The element chlorine occurs in nature as a mixture of two isotopes. Chlorine-35 has an atomic mass of 34.969 amu and makes up 75.77% of chlorine atoms. Chlorine-37 atoms make up the remaining 24.23% of all chlorine. Use the average atomic mass of chlorine from the periodic table to calculate the atomic mass of Cl-37 atoms. 

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