why sodium has atomic mass equal to 23 rather than 22 ,also for chlorine 35 rather than 34, and how can we deduce formuula mass of NaCl.

Asked by Tariqulislam786 | 17th May, 2015, 11:57: AM

Expert Answer:

Mass number = Total number of protons + Total number of neutrons

Sodium atom has  11 protons and 12 neutrons in its nucleus.

Hence Mass number = 11+ 12 = 23 amu

So the total number of protons and neutrons in a nucleus is numerically equal to the relative atomic mass of the atom.

Similarly chlorine has 17 protons and 18 neutrons

So mass number of chlorine atom = 17+ 18 = 35 amu

From the data we can calculate the mass number of NaCl

Mass of NaCl = 23 + 35 = 58 amu

Answered by Vaibhav Chavan | 17th May, 2015, 02:36: PM

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