Cl Mass Number

Chlorine

Explanation

Chlorineis a chemical element with the symbol Cland it has atomic number 17. Chlorine is the second member of halogen group ithas similar properties like fluorine, bromine and iodine. Chlorine haselectronic configuration [Ne] 3s²3p⁵withthe seven electrons in the third outermost shell acting as its valenceelectrons.

Chlorine has two stable isotopes: chlorine – 35and chorine – 37. The atomic weight of chlorine given on the periodic table is35.47 u. Different isotopes have different relative abundances ,chlorine – 35has a relative abundance of 75.76% ,whereas chlorine – 37 has a relativeabundance of 24.24%. Chlorine -35 is about 3 times more abundant than chlorine– 37, the weighted average is closer to 35 than 37.

Naturally occurring chlorine consists of 35 Cl (mass 34.96885 amu) and 37 Cl (mass 36.96590 amu), with an average mass of 35.453 amu. What is the percent composition of Cl in terms of these two isotopes? Favorite Answer Basically speaking, Chlorine has 2 isotopes Cl-35 and Cl-37. The mass number of an element is the average mass of all the existing isotopes. Roughly the ratio of abundance of Cl-35.

The mass spectrum of Chlorine

Chlorine is such an element which contain morethan one atom per molecule. It has two isotopes Cl-35 and Cl-37, so it contain3 atoms of Cl-35 and 1 atom of Cl-37. It consist of molecules so when it passedinto the ionization chamber, the electrons are knocked off, and give molecularion, Cl₂⁺. The ions are not stable so some will formchlorine atom and a Cl⁺ion. This process is called fragmentation.

Cl Mass Number Rounded

Cl₂⁺→ Cl + Cl⁺

The Cl atom is neither accelerated nor deflected in the machine it is not ionized in the ionization chamber and simply lost. But Cl⁺ ions will pass through the machine and give lines at 35 and 37 it is depend upon isotopes.

Mass Spectrometry

Mass spectrometry is an important method which is used to identify elements and compounds by their mass spectrum. Mass spectrometry is a technique used to determine relative isotopic masses of different elements and relative abundance of the isotopes.

Inall types of mass spectroscopy they include vaporing atoms or molecules in highvacuum and create electron bombardment to generate a beam of positive ionscalled ionization. Mass spectrometer separates and counts the numbers ofdifferent positive ions particles are released, the resulting product from thedetector is known as mass spectrum (plural mass spectra).

Theseare different types of mass spectrometer:

Method No. 1. Deflection Mass Spectrometer:

It is also called as TOF type. Deflection mass spectrometer consists of ionization, acceleration the positive ions, which in turn deflection of ions and ion detection followed by deflection, separation and detection. The substance which is to be analyzed is injected in the high vacuum tube system which has extremely low pressure particles are ionized through colliding with beam of high speed electron.

In the above diagram the symbol K as sampleand Q as high voltage supply label. High voltage electron gun falls a beam ofhigh energy electrons from a heated metal element into the vaporized sampleunder analysis and causes ionization of the atoms or molecule form positiveions. The collision of high energy electrons with atoms or molecules causesanother electron to remove the particle as positively charged particle. The sample must in the gaseous phase, In caseof chlorine:

Cl _(g) + e^– = Cl ⁺_(g) + e^–

The low pressure vacuum is needed to stop theions to collide with air particles which affect the motion of particles toreach the ion detector system.

Negativeplate as P in above diagram. Negative plates accelerate the positive ions tomove through the tube. The moving charge particles create a magnetic fieldaround itself which interact with magnetic field of the system at point R [2].

Deflectionof ions due to magnetic field is label as R. Magnetic field deflect the mono-positiveions according to their increasing mass towards the ion detection system. Alllike mass particles move down the tube. Ion detection system is labelled as N. ionsstrike the ion detection system where they generate a small electrical current.This small current convert into electronic signals appear as ion peaks whichsent to computer for analysis and display as mass spectrum. The data isdisplayed as m/z versus peak height.m/z means relative mass over chargewhich help to know relative atomic mass of ionized particle.

Cl 37 Mass

The mass spectrum of chlorine is good example of molecular element. Chlorine has two stable isotopes; chlorine-37 (25%) and chlorine -35 (75%).There are five main peaks of isotopes of chlorine of various isotopic monatomic ions.

[³⁷Cl₂]⁺ mz =74 ( molecular ion)
[³⁷Cl ³⁵Cl]⁺ mz = 72
[³⁵Cl₂]⁺ m/z=70 (molecular ion)
[³⁷Cl]⁺m/z = 37 (monatomic ion)
[³⁵Cl]⁺ m/z =35 (monoatomic ion)

Thepresence of five peaks for chlorine shows the ratio of heights for peaks 1 and2 is 3: 1. For bimolecular ions, ¾ of the chlorine isotopes are Cl 35 and ¼ ofthe isotope of chlorine is cl37.

Themass spectrum of an organic compound having chlorine atoms also show differentmass spectrum. Organic compound having one chlorine atom show molecular peaksM+ and M+2.the molecular ion containing ³⁵Cl isotope has relativeatomic mass 78 whereas molecular ion containing ³⁷Cl has relativeatomic mass 80.

Mass spectrum of 2-chloropropane is given below. In this mass spectrum the peak heights of chlorine are in the ratio of 3:1 which show that lighter isotope of chlorine is attached with more number of molecules as compared to the heavier isotope. The fragmentation of 2-chloropropane formed are

Same pattern of peaks are observed at m/z = 63 and m/z = 65 due to chlorine atoms which is attached to CH₃CH forming positive ion.

The organic compound having two chlorine atoms show three peaks due different combinations of isotopes of chlorine are attached with carbon and hydrogen. The ratio observed in this case is 9:6:1.the compound containing 2 chlorine atom have difference in ratio due to isotopes attached with fragments.

Method No. 2. Time of Flight (TOF) Mass Spectrometer

The principle of this method is also include ionization, acceleration to donate constant kinetic energy to all ions, ions drift, ions detection and also data analysis, all things are controlled and carried out with the help of computers now a days.

Theions are formed similarly through electron bombardment and the ions which areproduced as a result of bombardment are accelerated between electricallycharged plates. The sample must be in gaseous form, laser beam is used toaccelerate electrons and produced positive ions. In this process magnetic fieldis not used to separate the positive ions.

Inthis process the ionized particle which has smaller mass has smaller time offlight in the drift region so in this case ions are separate on the base oftheir time of flight.

Cl Mass Number

t=K_inst √(m/q)

t=timeof flight

m=massof ion

q=chargeon ion

√=squareroot of

K_inst= a proportionality constant based on the instrument settings andcharacteristics e.g. the electric field strength, length of analyzing tube etc.

References:

http://www.docbrown.info/page04/4_71atomMSintro.htm

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Learning Objective

Determine the relationship between the mass number of an atom, its atomic number, its atomic mass, and its number of subatomic particles

Key Points

35 Cl Mass Number

Neutral atoms of each element contain an equal number of protons and electrons.
The number of protons determines an element’s atomic number and is used to distinguish one element from another.
The number of neutrons is variable, resulting in isotopes, which are different forms of the same atom that vary only in the number of neutrons they possess.
Together, the number of protons and the number of neutrons determine an element’s mass number.
Since an element’s isotopes have slightly different mass numbers, the atomic mass is calculated by obtaining the mean of the mass numbers for its isotopes.

Terms

atomic massThe average mass of an atom, taking into account all its naturally occurring isotopes.
mass numberThe sum of the number of protons and the number of neutrons in an atom.
atomic numberThe number of protons in an atom.

Atomic Number

Chlorine Mass

Neutral atoms of an element contain an equal number of protons and electrons. The number of protons determines an element’s atomic number (Z) and distinguishes one element from another. For example, carbon’s atomic number (Z) is 6 because it has 6 protons. The number of neutrons can vary to produce isotopes, which are atoms of the same element that have different numbers of neutrons. The number of electrons can also be different in atoms of the same element, thus producing ions (charged atoms). For instance, iron, Fe, can exist in its neutral state, or in the +2 and +3 ionic states.

Mass Number

An element’s mass number (A) is the sum of the number of protons and the number of neutrons. The small contribution of mass from electrons is disregarded in calculating the mass number. This approximation of mass can be used to easily calculate how many neutrons an element has by simply subtracting the number of protons from the mass number. Protons and neutrons both weigh about one atomic mass unit or amu. Isotopes of the same element will have the same atomic number but different mass numbers.

Scientists determine the atomic mass by calculating the mean of the mass numbers for its naturally-occurring isotopes. Often, the resulting number contains a decimal. For example, the atomic mass of chlorine (Cl) is 35.45 amu because chlorine is composed of several isotopes, some (the majority) with an atomic mass of 35 amu (17 protons and 18 neutrons) and some with an atomic mass of 37 amu (17 protons and 20 neutrons).

Given an atomic number (Z) and mass number (A), you can find the number of protons, neutrons, and electrons in a neutral atom. For example, a lithium atom (Z=3, A=7 amu) contains three protons (found from Z), three electrons (as the number of protons is equal to the number of electrons in an atom), and four neutrons (7 – 3 = 4).

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http://www.boundless.com/
Boundless Learning
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http://en.wiktionary.org/wiki/atomic_number
Wiktionary
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http://www.boundless.com//biology/definition/atomic-mass–2
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“A-level Chemistry/OCR/Atoms, Bonds and Groups/Atoms and Reactions/Atoms.”

http://en.wikibooks.org/wiki/A-level_Chemistry/OCR/Atoms,_Bonds_and_Groups/Atoms_and_Reactions/Atoms
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http://cnx.org/content/m44390/latest/?collection=col11448/latest
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Atomic Number Of Mn

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