while calculating the formula mass unit of CaCl2 why we will take the atomic mass of chlorine as 35.5 and not as 35 ? pls explain. The most explained and appropriate answer will be marked as the brainliest !!! give reasons for your answer.
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It is because of something called isotopes. Isotopes are atoms with the same number of protons (in the case ofchlorine that means 17 protons) but different numbers of neutrons.Chlorine has two common isotopes,Chlorine-35 and Chlorine-37.
Chlorine-35 has 17 protons and 18 neutrons and occurs in nature about 75% of the time. Chlorine-37 has 17 protons and 20 neutrons and occurs in nature about 25% of the time. That means that in any mixture of pure chlorine that can be isolated from all other elements there is 75% Chlorine-35 and 25% Chlorine-37. So, when the mass of chlorine is measured using an instrument called a mass spectrometer the result is a mass of 35.5. The atomic weight, or as it is properly called, the RELATIVE atomic mass, is a weighted average of the masses of all the isotopes of chlorine. Relative Atomic Mass = (75/100 x 35) + (25/100 x 37) = 35.5
Isotopes of any element behave the same chemically because neutrons do not have any charge. Both isotopes of chlorine have 17 positive charges from the 17 protons in the nucleus and 17 negative charges from the electrons in the surrounding orbitals, and so it does not matter which isotope is in a chemical reaction.
Chlorine in natural state comprises two isotopes of atomic masses 35 u and 37 u in the ratio 3:1. Hence, the atomic mass of chlorine is taken as the average of atomic masses of two isotopes. Thus,
Average atomic mass =
35 x 3/4 + 37 x 1/4 = 35.5 u
I hope it will clear ur prblm...
Chlorine-35 has 17 protons and 18 neutrons and occurs in nature about 75% of the time. Chlorine-37 has 17 protons and 20 neutrons and occurs in nature about 25% of the time. That means that in any mixture of pure chlorine that can be isolated from all other elements there is 75% Chlorine-35 and 25% Chlorine-37. So, when the mass of chlorine is measured using an instrument called a mass spectrometer the result is a mass of 35.5. The atomic weight, or as it is properly called, the RELATIVE atomic mass, is a weighted average of the masses of all the isotopes of chlorine. Relative Atomic Mass = (75/100 x 35) + (25/100 x 37) = 35.5
Isotopes of any element behave the same chemically because neutrons do not have any charge. Both isotopes of chlorine have 17 positive charges from the 17 protons in the nucleus and 17 negative charges from the electrons in the surrounding orbitals, and so it does not matter which isotope is in a chemical reaction.
Chlorine in natural state comprises two isotopes of atomic masses 35 u and 37 u in the ratio 3:1. Hence, the atomic mass of chlorine is taken as the average of atomic masses of two isotopes. Thus,
Average atomic mass =
35 x 3/4 + 37 x 1/4 = 35.5 u
I hope it will clear ur prblm...
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